Volume
LIPIcs, Volume 235
28th International Conference on Principles and Practice of Constraint Programming (CP 2022)
Event
CP 2022, July 31 to August 8, 2022, Haifa, IsraelEditor
Publication Details
- published at: 2022-07-23
- Publisher: Schloss Dagstuhl – Leibniz-Zentrum für Informatik
- ISBN: 978-3-95977-240-2
- DBLP: db/conf/cp/cp2022
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Document
Complete Volume
LIPIcs, Volume 235, CP 2022, Complete Volume
Abstract
LIPIcs, Volume 235, CP 2022, Complete Volume
Cite as
28th International Conference on Principles and Practice of Constraint Programming (CP 2022). Leibniz International Proceedings in Informatics (LIPIcs), Volume 235, pp. 1-692, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2022)
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@Proceedings{solnon:LIPIcs.CP.2022,
title = {{LIPIcs, Volume 235, CP 2022, Complete Volume}},
booktitle = {28th International Conference on Principles and Practice of Constraint Programming (CP 2022)},
pages = {1--692},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-240-2},
ISSN = {1868-8969},
year = {2022},
volume = {235},
editor = {Solnon, Christine},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.CP.2022},
URN = {urn:nbn:de:0030-drops-166285},
doi = {10.4230/LIPIcs.CP.2022},
annote = {Keywords: LIPIcs, Volume 235, CP 2022, Complete Volume}
}
Document
Front Matter
Front Matter, Table of Contents, Preface, Conference Organization
Abstract
Front Matter, Table of Contents, Preface, Conference Organization
Cite as
28th International Conference on Principles and Practice of Constraint Programming (CP 2022). Leibniz International Proceedings in Informatics (LIPIcs), Volume 235, pp. 0:i-0:xviii, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2022)
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@InProceedings{solnon:LIPIcs.CP.2022.0,
author = {Solnon, Christine},
title = {{Front Matter, Table of Contents, Preface, Conference Organization}},
booktitle = {28th International Conference on Principles and Practice of Constraint Programming (CP 2022)},
pages = {0:i--0:xviii},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-240-2},
ISSN = {1868-8969},
year = {2022},
volume = {235},
editor = {Solnon, Christine},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.CP.2022.0},
URN = {urn:nbn:de:0030-drops-166292},
doi = {10.4230/LIPIcs.CP.2022.0},
annote = {Keywords: Front Matter, Table of Contents, Preface, Conference Organization}
}
Document
Invited Talk
All Questions Answered (Invited Talk)
Abstract
During the past two years, the speaker has been drafting Section 7.2.2.3 of "The Art of Computer Programming", which is intended to be a solid introduction to techniques for solving Constraint Satisfaction Problems. The CP 2022 conference is an excellent opportunity for him to get feedback from the leading experts on the subject, and so he was delighted to learn that the organizers were also interested in hearing a few words from him.
Rather than giving a canned lecture, he much prefers to let the audience choose the topics, and for all questions to be kept a secret from him until the lecture is actually in progress. (He believes that people often learn more from answers that are spontaneously fumbled than from responses that are carefully preplanned.)
Questions related to constraints will naturally be quite welcome, but questions on any subject whatsoever will not be ducked! He'll try to answer them all as best he can, without spending a great deal of time on any one topic, unless there is special interest to go into more depth.
Meanwhile he hopes to have drafted some notes for circulation before the conference begins, in case some attendees might wish to focus some of their questions on expository material related to his forthcoming book, either during this session or informally afterwards.
Warning: His least favorite questions have the form "What is your favorite X?" If you want to ask such questions, please try to do it cleverly so that he doesn't have to choose between different things that he loves in different ways.
Cite as
Donald E. Knuth. All Questions Answered (Invited Talk). In 28th International Conference on Principles and Practice of Constraint Programming (CP 2022). Leibniz International Proceedings in Informatics (LIPIcs), Volume 235, p. 1:1, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2022)
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@InProceedings{knuth:LIPIcs.CP.2022.1,
author = {Knuth, Donald E.},
title = {{All Questions Answered}},
booktitle = {28th International Conference on Principles and Practice of Constraint Programming (CP 2022)},
pages = {1:1--1:1},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-240-2},
ISSN = {1868-8969},
year = {2022},
volume = {235},
editor = {Solnon, Christine},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.CP.2022.1},
URN = {urn:nbn:de:0030-drops-166305},
doi = {10.4230/LIPIcs.CP.2022.1},
annote = {Keywords: The Art of Computer Programming}
}
Document
Fixed-Template Promise Model Checking Problems
Abstract
The fixed-template constraint satisfaction problem (CSP) can be seen as the problem of deciding whether a given primitive positive first-order sentence is true in a fixed structure (also called model). We study a class of problems that generalizes the CSP simultaneously in two directions: we fix a set ℒ of quantifiers and Boolean connectives, and we specify two versions of each constraint, one strong and one weak. Given a sentence which only uses symbols from ℒ, the task is to distinguish whether the sentence is true in the strong sense, or it is false even in the weak sense.
We classify the computational complexity of these problems for the existential positive equality-free fragment of first-order logic, i.e., ℒ = {∃,∧,∨}, and we prove some upper and lower bounds for the positive equality-free fragment, ℒ = {∃,∀,∧,∨}. The partial results are sufficient, e.g., for all extensions of the latter fragment.
Cite as
Kristina Asimi, Libor Barto, and Silvia Butti. Fixed-Template Promise Model Checking Problems. In 28th International Conference on Principles and Practice of Constraint Programming (CP 2022). Leibniz International Proceedings in Informatics (LIPIcs), Volume 235, pp. 2:1-2:17, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2022)
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@InProceedings{asimi_et_al:LIPIcs.CP.2022.2,
author = {Asimi, Kristina and Barto, Libor and Butti, Silvia},
title = {{Fixed-Template Promise Model Checking Problems}},
booktitle = {28th International Conference on Principles and Practice of Constraint Programming (CP 2022)},
pages = {2:1--2:17},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-240-2},
ISSN = {1868-8969},
year = {2022},
volume = {235},
editor = {Solnon, Christine},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.CP.2022.2},
URN = {urn:nbn:de:0030-drops-166310},
doi = {10.4230/LIPIcs.CP.2022.2},
annote = {Keywords: Model Checking Problem, First-Order Logic, Promise Constraint Satisfaction Problem, Multi-Homomorphism}
}
Document
Improved Sample Complexity Bounds for Branch-And-Cut
Abstract
The branch-and-cut algorithm for integer programming has a wide variety of tunable parameters that have a huge impact on its performance, but which are challenging to tune by hand. An increasingly popular approach is to use machine learning to configure these parameters based on a training set of integer programs from the application domain. We bound how large the training set should be to ensure that for any configuration, its average performance over the training set is close to its expected future performance. Our guarantees apply to parameters that control the most important aspects of branch-and-cut: node selection, branching constraint selection, and cut selection, and are sharper and more general than those from prior research.
Cite as
Maria-Florina Balcan, Siddharth Prasad, Tuomas Sandholm, and Ellen Vitercik. Improved Sample Complexity Bounds for Branch-And-Cut. In 28th International Conference on Principles and Practice of Constraint Programming (CP 2022). Leibniz International Proceedings in Informatics (LIPIcs), Volume 235, pp. 3:1-3:19, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2022)
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@InProceedings{balcan_et_al:LIPIcs.CP.2022.3,
author = {Balcan, Maria-Florina and Prasad, Siddharth and Sandholm, Tuomas and Vitercik, Ellen},
title = {{Improved Sample Complexity Bounds for Branch-And-Cut}},
booktitle = {28th International Conference on Principles and Practice of Constraint Programming (CP 2022)},
pages = {3:1--3:19},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-240-2},
ISSN = {1868-8969},
year = {2022},
volume = {235},
editor = {Solnon, Christine},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.CP.2022.3},
URN = {urn:nbn:de:0030-drops-166321},
doi = {10.4230/LIPIcs.CP.2022.3},
annote = {Keywords: Automated algorithm configuration, integer programming, machine learning theory, tree search, branch-and-bound, branch-and-cut, cutting planes, sample complexity, generalization guarantees, data-driven algorithm design}
}
Document
Weisfeiler-Leman Invariant Promise Valued CSPs
Abstract
In a recent line of work, Butti and Dalmau have shown that a fixed-template Constraint Satisfaction Problem is solvable by a certain natural linear programming relaxation (equivalent to the basic linear programming relaxation) if and only if it is solvable on a certain distributed network, and this happens if and only if its set of Yes instances is closed under Weisfeiler-Leman equivalence. We generalize this result to the much broader framework of fixed-template Promise Valued Constraint Satisfaction Problems. Moreover, we show that two commonly used linear programming relaxations are no longer equivalent in this broader framework.
Cite as
Libor Barto and Silvia Butti. Weisfeiler-Leman Invariant Promise Valued CSPs. In 28th International Conference on Principles and Practice of Constraint Programming (CP 2022). Leibniz International Proceedings in Informatics (LIPIcs), Volume 235, pp. 4:1-4:17, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2022)
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@InProceedings{barto_et_al:LIPIcs.CP.2022.4,
author = {Barto, Libor and Butti, Silvia},
title = {{Weisfeiler-Leman Invariant Promise Valued CSPs}},
booktitle = {28th International Conference on Principles and Practice of Constraint Programming (CP 2022)},
pages = {4:1--4:17},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-240-2},
ISSN = {1868-8969},
year = {2022},
volume = {235},
editor = {Solnon, Christine},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.CP.2022.4},
URN = {urn:nbn:de:0030-drops-166332},
doi = {10.4230/LIPIcs.CP.2022.4},
annote = {Keywords: Promise Valued Constraint Satisfaction Problem, Linear programming relaxation, Distributed algorithms, Symmetric fractional polymorphisms, Color refinement algorithm}
}
Document
Trajectory Optimization for Safe Navigation in Maritime Traffic Using Historical Data
Abstract
Increasing maritime trade often results in congestion in busy ports, thereby necessitating planning methods to avoid close quarter risky situations among vessels. Rapid digitization and automation of port operations and vessel navigation provide unique opportunities for significantly improving navigation safety. Our key contributions are as follows. First, given a set of future candidate trajectories for vessels in a traffic hotspot zone, we develop a multiagent trajectory optimization method to choose trajectories that result in the best overall close quarter risk reduction. Our novel MILP-based optimization method is more than an order-of-magnitude faster than a standard MILP for this problem, and runs in near real-time. Second, although automation has improved in maritime operations, current vessel traffic systems (in our case study of a busy Asian port) predict only a single future trajectory of a vessel based on linear extrapolation. Therefore, using historical data we learn a generative model that predicts multiple possible future trajectories of each vessel in a given traffic hotspot, reflecting past vessel movement patterns, and integrate it with our trajectory optimizer. Third, we validate our trajectory optimization and generative model extensively using a real world maritime traffic dataset containing 6 million Automated Identification System (AIS) data records detailing vessel movements over 1.5 years from one of the world’s busiest ports, demonstrating effective risk reduction.
Cite as
Chaithanya Basrur, Arambam James Singh, Arunesh Sinha, Akshat Kumar, and T. K. Satish Kumar. Trajectory Optimization for Safe Navigation in Maritime Traffic Using Historical Data. In 28th International Conference on Principles and Practice of Constraint Programming (CP 2022). Leibniz International Proceedings in Informatics (LIPIcs), Volume 235, pp. 5:1-5:17, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2022)
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@InProceedings{basrur_et_al:LIPIcs.CP.2022.5,
author = {Basrur, Chaithanya and Singh, Arambam James and Sinha, Arunesh and Kumar, Akshat and Kumar, T. K. Satish},
title = {{Trajectory Optimization for Safe Navigation in Maritime Traffic Using Historical Data}},
booktitle = {28th International Conference on Principles and Practice of Constraint Programming (CP 2022)},
pages = {5:1--5:17},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-240-2},
ISSN = {1868-8969},
year = {2022},
volume = {235},
editor = {Solnon, Christine},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.CP.2022.5},
URN = {urn:nbn:de:0030-drops-166341},
doi = {10.4230/LIPIcs.CP.2022.5},
annote = {Keywords: Multi-Agent Path Coordination, Maritime Traffic Control}
}
Document
Acquiring Maps of Interrelated Conjectures on Sharp Bounds
Abstract
To automate the discovery of conjectures on combinatorial objects, we introduce the concept of a map of sharp bounds on characteristics of combinatorial objects, that provides a set of interrelated sharp bounds for these combinatorial objects. We then describe a Bound Seeker, a CP-based system, that gradually acquires maps of conjectures. The system was tested for searching conjectures on bounds on characteristics of digraphs: it constructs sixteen maps involving 431 conjectures on sharp lower and upper-bounds on eight digraph characteristics.
Cite as
Nicolas Beldiceanu, Jovial Cheukam-Ngouonou, Rémi Douence, Ramiz Gindullin, and Claude-Guy Quimper. Acquiring Maps of Interrelated Conjectures on Sharp Bounds. In 28th International Conference on Principles and Practice of Constraint Programming (CP 2022). Leibniz International Proceedings in Informatics (LIPIcs), Volume 235, pp. 6:1-6:18, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2022)
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@InProceedings{beldiceanu_et_al:LIPIcs.CP.2022.6,
author = {Beldiceanu, Nicolas and Cheukam-Ngouonou, Jovial and Douence, R\'{e}mi and Gindullin, Ramiz and Quimper, Claude-Guy},
title = {{Acquiring Maps of Interrelated Conjectures on Sharp Bounds}},
booktitle = {28th International Conference on Principles and Practice of Constraint Programming (CP 2022)},
pages = {6:1--6:18},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-240-2},
ISSN = {1868-8969},
year = {2022},
volume = {235},
editor = {Solnon, Christine},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.CP.2022.6},
URN = {urn:nbn:de:0030-drops-166353},
doi = {10.4230/LIPIcs.CP.2022.6},
annote = {Keywords: Acquisition of conjectures, digraphs, bounds}
}
Document
Parallel Hybrid Best-First Search
Abstract
While processor frequency has stagnated over the past two decades, the number of available cores in servers or clusters is still growing, offering the opportunity for significant speed-up in combinatorial optimization. Parallelization of exact methods remains a difficult challenge. We revisit the concept of parallel Branch-and-Bound in the framework of Cost Function Networks. We show how to adapt the anytime Hybrid Best-First Search algorithm in a Master-Worker protocol. The resulting parallel algorithm achieves good load-balancing without introducing new parameters to be tuned as is the case, for example, in Embarrassingly Parallel Search (EPS). It has also a small overhead due to its light communication messages. We performed an experimental evaluation on several benchmarks, comparing our parallel algorithm to its sequential version. We observed linear speed-up in some cases. Our approach compared favourably to the EPS approach and also to a state-of-the-art parallel exact integer programming solver.
Cite as
Abdelkader Beldjilali, Pierre Montalbano, David Allouche, George Katsirelos, and Simon de Givry. Parallel Hybrid Best-First Search. In 28th International Conference on Principles and Practice of Constraint Programming (CP 2022). Leibniz International Proceedings in Informatics (LIPIcs), Volume 235, pp. 7:1-7:10, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2022)
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@InProceedings{beldjilali_et_al:LIPIcs.CP.2022.7,
author = {Beldjilali, Abdelkader and Montalbano, Pierre and Allouche, David and Katsirelos, George and de Givry, Simon},
title = {{Parallel Hybrid Best-First Search}},
booktitle = {28th International Conference on Principles and Practice of Constraint Programming (CP 2022)},
pages = {7:1--7:10},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-240-2},
ISSN = {1868-8969},
year = {2022},
volume = {235},
editor = {Solnon, Christine},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.CP.2022.7},
URN = {urn:nbn:de:0030-drops-166362},
doi = {10.4230/LIPIcs.CP.2022.7},
annote = {Keywords: Combinatorial Optimization, Parallel Branch-and-Bound, CFN}
}
Document
Learning MAX-SAT Models from Examples Using Genetic Algorithms and Knowledge Compilation
Abstract
Many real-world problems can be effectively solved by means of combinatorial optimization. However, appropriate models to give to a solver are not always available, and sometimes must be learned from historical data. Although some research has been done in this area, the task of learning (weighted partial) MAX-SAT models has not received much attention thus far, even though such models can be used in many real-world applications. Furthermore, most existing work is limited to learning models from non-contextual data, where instances are labeled as solutions and non-solutions, but without any specification of the contexts in which those labels apply. A recent approach named hassle-sls has addressed these limitations: it can jointly learn hard constraints and weighted soft constraints from labeled contextual examples. However, it is hindered by long runtimes, as evaluating even a single candidate MAX-SAT model requires solving as many models as there are contexts in the training data, which quickly becomes highly expensive when the size of the model increases. In this work, we address these runtime issues. To this end, we make two contributions. First, we propose a faster model evaluation procedure that makes use of knowledge compilation. Second, we propose a genetic algorithm named hassle-gen that decreases the number of evaluations needed to find good models. We experimentally show that both contributions improve on the state of the art by speeding up learning, which in turn allows higher-quality MAX-SAT models to be found within a given learning time budget.
Cite as
Senne Berden, Mohit Kumar, Samuel Kolb, and Tias Guns. Learning MAX-SAT Models from Examples Using Genetic Algorithms and Knowledge Compilation. In 28th International Conference on Principles and Practice of Constraint Programming (CP 2022). Leibniz International Proceedings in Informatics (LIPIcs), Volume 235, pp. 8:1-8:17, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2022)
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@InProceedings{berden_et_al:LIPIcs.CP.2022.8,
author = {Berden, Senne and Kumar, Mohit and Kolb, Samuel and Guns, Tias},
title = {{Learning MAX-SAT Models from Examples Using Genetic Algorithms and Knowledge Compilation}},
booktitle = {28th International Conference on Principles and Practice of Constraint Programming (CP 2022)},
pages = {8:1--8:17},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-240-2},
ISSN = {1868-8969},
year = {2022},
volume = {235},
editor = {Solnon, Christine},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.CP.2022.8},
URN = {urn:nbn:de:0030-drops-166373},
doi = {10.4230/LIPIcs.CP.2022.8},
annote = {Keywords: Machine learning, constraint learning, MAX-SAT}
}
Document
Complexity of Minimum-Size Arc-Inconsistency Explanations
Abstract
Explaining the outcome of programs has become one of the main concerns in AI research. In constraint programming, a user may want the system to explain why a given variable assignment is not feasible or how it came to the conclusion that the problem does not have any solution. One solution to the latter is to return to the user a sequence of simple reasoning steps that lead to inconsistency. Arc consistency is a well-known form of reasoning that can be understood by a human. We consider explanations as sequences of propagation steps of a constraint on a variable (i.e. the ubiquitous revise function in arc consistency algorithms) that lead to inconsistency. We characterize, on binary CSPs, cases for which providing a shortest such explanation is easy: when domains are Boolean or when variables have maximum degree two. However, these polynomial cases are tight. Providing a shortest explanation is NP-hard if the maximum degree is three, even if the number of variables is bounded, or if domain size is bounded by three. It remains NP-hard on trees, despite the fact that arc consistency is a decision procedure on trees. Finally, the problem is not FPT-approximable unless the Gap-ETH is false.
Cite as
Christian Bessiere, Clément Carbonnel, Martin C. Cooper, and Emmanuel Hebrard. Complexity of Minimum-Size Arc-Inconsistency Explanations. In 28th International Conference on Principles and Practice of Constraint Programming (CP 2022). Leibniz International Proceedings in Informatics (LIPIcs), Volume 235, pp. 9:1-9:14, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2022)
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@InProceedings{bessiere_et_al:LIPIcs.CP.2022.9,
author = {Bessiere, Christian and Carbonnel, Cl\'{e}ment and Cooper, Martin C. and Hebrard, Emmanuel},
title = {{Complexity of Minimum-Size Arc-Inconsistency Explanations}},
booktitle = {28th International Conference on Principles and Practice of Constraint Programming (CP 2022)},
pages = {9:1--9:14},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-240-2},
ISSN = {1868-8969},
year = {2022},
volume = {235},
editor = {Solnon, Christine},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.CP.2022.9},
URN = {urn:nbn:de:0030-drops-166380},
doi = {10.4230/LIPIcs.CP.2022.9},
annote = {Keywords: Constraint programming, constraint propagation, minimum explanations, complexity}
}
Document
A Constraint Programming Approach to Ship Refit Project Scheduling
Abstract
Ship refit projects require ongoing plan management to adapt to arising work and disruptions. Planners must sequence work activities in the best order possible to complete the project in the shortest time or within a defined period while minimizing overtime costs. Activity scheduling must consider milestones, resource availability constraints, and precedence relations. We propose a constraint programming approach for detailed ship refit planning at two granularity levels, daily and hourly schedule. The problem was modeled using the Cumulative global constraint, and the Solution-Based Phase Saving heuristic was used to speedup the search, thus achieving the industrialization goals. Based on the evaluation of seven realistic instances over three objectives, the heuristic strategy proved to be significantly faster to find better solutions than using a baseline search strategy. The method was integrated into Refit Optimizer, a cloud-based prototype solution that can import projects from Primavera P6 and optimize plans.
Cite as
Raphaël Boudreault, Vanessa Simard, Daniel Lafond, and Claude-Guy Quimper. A Constraint Programming Approach to Ship Refit Project Scheduling. In 28th International Conference on Principles and Practice of Constraint Programming (CP 2022). Leibniz International Proceedings in Informatics (LIPIcs), Volume 235, pp. 10:1-10:16, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2022)
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@InProceedings{boudreault_et_al:LIPIcs.CP.2022.10,
author = {Boudreault, Rapha\"{e}l and Simard, Vanessa and Lafond, Daniel and Quimper, Claude-Guy},
title = {{A Constraint Programming Approach to Ship Refit Project Scheduling}},
booktitle = {28th International Conference on Principles and Practice of Constraint Programming (CP 2022)},
pages = {10:1--10:16},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-240-2},
ISSN = {1868-8969},
year = {2022},
volume = {235},
editor = {Solnon, Christine},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.CP.2022.10},
URN = {urn:nbn:de:0030-drops-166396},
doi = {10.4230/LIPIcs.CP.2022.10},
annote = {Keywords: Ship refit, planning, project management, constraint programming, scheduling, optimization, resource-constrained project scheduling problem}
}
Document
On Redundancy in Constraint Satisfaction Problems
Abstract
A constraint language Γ has non-redundancy f(n) if every instance of CSP(Γ) with n variables contains at most f(n) non-redundant constraints. If Γ has maximum arity r then it has non-redundancy O(n^r), but there are notable examples for which this upper bound is far from the best possible. In general, the non-redundancy of constraint languages is poorly understood and little is known beyond the trivial bounds Ω(n) and O(n^r).
In this paper, we introduce an elementary algebraic framework dedicated to the analysis of the non-redundancy of constraint languages. This framework relates redundancy-preserving reductions between constraint languages to closure operators known as pattern partial polymorphisms, which can be interpreted as generic mechanisms to generate redundant constraints in CSP instances. We illustrate the power of this framework by deriving a simple characterisation of all languages of arity r having non-redundancy Θ(n^r).
Cite as
Clément Carbonnel. On Redundancy in Constraint Satisfaction Problems. In 28th International Conference on Principles and Practice of Constraint Programming (CP 2022). Leibniz International Proceedings in Informatics (LIPIcs), Volume 235, pp. 11:1-11:15, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2022)
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@InProceedings{carbonnel:LIPIcs.CP.2022.11,
author = {Carbonnel, Cl\'{e}ment},
title = {{On Redundancy in Constraint Satisfaction Problems}},
booktitle = {28th International Conference on Principles and Practice of Constraint Programming (CP 2022)},
pages = {11:1--11:15},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-240-2},
ISSN = {1868-8969},
year = {2022},
volume = {235},
editor = {Solnon, Christine},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.CP.2022.11},
URN = {urn:nbn:de:0030-drops-166409},
doi = {10.4230/LIPIcs.CP.2022.11},
annote = {Keywords: Constraint satisfaction problem, redundancy, universal algebra, extremal combinatorics}
}
Document
From Crossing-Free Resolution to Max-SAT Resolution
Abstract
Adapting a SAT resolution proof into a Max-SAT resolution proof without considerably increasing its size is an open problem. Read-once resolution, where each clause is used at most once in the proof, represents the only fragment of resolution for which an adaptation using exclusively Max-SAT resolution is known and trivial. Proofs containing non read-once clauses are difficult to adapt because the Max-SAT resolution rule replaces the premises by the conclusions. This paper contributes to this open problem by defining, for the first time since the introduction of Max-SAT resolution, a new fragment of resolution whose proofs can be adapted to Max-SAT resolution proofs without substantially increasing their size. In this fragment, called crossing-free resolution, non read-once clauses are used independently to infer new information thus enabling to bring along each non read-once clause while unfolding the proof until a substitute is required.
Cite as
Mohamed Sami Cherif, Djamal Habet, and Matthieu Py. From Crossing-Free Resolution to Max-SAT Resolution. In 28th International Conference on Principles and Practice of Constraint Programming (CP 2022). Leibniz International Proceedings in Informatics (LIPIcs), Volume 235, pp. 12:1-12:17, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2022)
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@InProceedings{cherif_et_al:LIPIcs.CP.2022.12,
author = {Cherif, Mohamed Sami and Habet, Djamal and Py, Matthieu},
title = {{From Crossing-Free Resolution to Max-SAT Resolution}},
booktitle = {28th International Conference on Principles and Practice of Constraint Programming (CP 2022)},
pages = {12:1--12:17},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-240-2},
ISSN = {1868-8969},
year = {2022},
volume = {235},
editor = {Solnon, Christine},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.CP.2022.12},
URN = {urn:nbn:de:0030-drops-166412},
doi = {10.4230/LIPIcs.CP.2022.12},
annote = {Keywords: Satisfiability, Proof, Max-SAT Resolution}
}
Document
Isomorphisms Between STRIPS Problems and Sub-Problems
Abstract
Determining whether two STRIPS planning instances are isomorphic is the simplest form of comparison between planning instances. It is also a particular case of the problem concerned with finding an isomorphism between a planning instance P and a sub-instance of another instance P'. One application of such an isomorphism is to efficiently produce a compiled form containing all solutions to P from a compiled form containing all solutions to P'. In this paper, we study the complexity of both problems. We show that the former is GI-complete, and can thus be solved, in theory, in quasi-polynomial time. While we prove the latter to be NP-complete, we propose an algorithm to build an isomorphism, when possible. We report extensive experimental trials on benchmark problems which demonstrate conclusively that applying constraint propagation in preprocessing can greatly improve the efficiency of a SAT solver.
Cite as
Martin C. Cooper, Arnaud Lequen, and Frédéric Maris. Isomorphisms Between STRIPS Problems and Sub-Problems. In 28th International Conference on Principles and Practice of Constraint Programming (CP 2022). Leibniz International Proceedings in Informatics (LIPIcs), Volume 235, pp. 13:1-13:16, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2022)
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@InProceedings{cooper_et_al:LIPIcs.CP.2022.13,
author = {Cooper, Martin C. and Lequen, Arnaud and Maris, Fr\'{e}d\'{e}ric},
title = {{Isomorphisms Between STRIPS Problems and Sub-Problems}},
booktitle = {28th International Conference on Principles and Practice of Constraint Programming (CP 2022)},
pages = {13:1--13:16},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-240-2},
ISSN = {1868-8969},
year = {2022},
volume = {235},
editor = {Solnon, Christine},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.CP.2022.13},
URN = {urn:nbn:de:0030-drops-166426},
doi = {10.4230/LIPIcs.CP.2022.13},
annote = {Keywords: planning, isomorphism, complexity, constraint propagation}
}
Document
Solving the Constrained Single-Row Facility Layout Problem with Decision Diagrams
Abstract
The Single-Row Facility Layout Problem is an NP-hard problem dealing with the ordering of departments with given lengths and pairwise traffic intensities in a facility. In this context, one seeks to minimize the sum of the distances between department pairs, weighted by the corresponding traffic intensities. Practical applications of this problem include the arrangement of rooms on a corridor in hospitals or offices, airplanes and gates in an airport or machines in a manufacture. This paper presents two novel exact models for the Constrained Single-Row Facility Layout Problem, a recent variant of the problem including positioning, ordering and adjacency constraints. On the one hand, the state-of-the-art mixed-integer programming model for the unconstrained problem is extended to incorporate the constraints. On the other hand, a decision diagram-based approach is described, based on an existing dynamic programming model for the unconstrained problem. Computational experiments show that both models outperform the only mixed-integer programming model in the literature, to the best of our knowledge. While the two models have execution times of the same order of magnitude, the decision diagram-based approach handles positioning constraints much better but the mixed-integer programming model has the advantage for ordering constraints.
Cite as
Vianney Coppé, Xavier Gillard, and Pierre Schaus. Solving the Constrained Single-Row Facility Layout Problem with Decision Diagrams. In 28th International Conference on Principles and Practice of Constraint Programming (CP 2022). Leibniz International Proceedings in Informatics (LIPIcs), Volume 235, pp. 14:1-14:18, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2022)
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@InProceedings{coppe_et_al:LIPIcs.CP.2022.14,
author = {Copp\'{e}, Vianney and Gillard, Xavier and Schaus, Pierre},
title = {{Solving the Constrained Single-Row Facility Layout Problem with Decision Diagrams}},
booktitle = {28th International Conference on Principles and Practice of Constraint Programming (CP 2022)},
pages = {14:1--14:18},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-240-2},
ISSN = {1868-8969},
year = {2022},
volume = {235},
editor = {Solnon, Christine},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.CP.2022.14},
URN = {urn:nbn:de:0030-drops-166433},
doi = {10.4230/LIPIcs.CP.2022.14},
annote = {Keywords: Discrete Optimization, Mixed-Integer Programming, Decision Diagrams, Constrained Single-Row Facility Layout Problem}
}
Document
Constraint Acquisition Based on Solution Counting
Abstract
We propose CABSC, a system that performs Constraint Acquisition Based on Solution Counting. In order to learn a Constraint Satisfaction Problem (CSP), the user provides positive examples and a Meta-CSP, i.e. a model of a combinatorial problem whose solution is a CSP. This Meta-CSP allows listing the potential constraints that can be part of the CSP the user wants to learn. It also allows stating the parameters of the constraints, such as the coefficients of a linear equation, and imposing constraints over these parameters. The CABSC reads the Meta-CSP using an augmented version of the language MiniZinc and returns the CSP that accepts the fewest solutions among the CSPs accepting all positive examples. This is done using a branch and bound where the bounding mechanism makes use of a model counter. Experiments show that CABSC is successful at learning constraints and their parameters from positive examples.
Cite as
Christopher Coulombe and Claude-Guy Quimper. Constraint Acquisition Based on Solution Counting. In 28th International Conference on Principles and Practice of Constraint Programming (CP 2022). Leibniz International Proceedings in Informatics (LIPIcs), Volume 235, pp. 15:1-15:16, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2022)
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@InProceedings{coulombe_et_al:LIPIcs.CP.2022.15,
author = {Coulombe, Christopher and Quimper, Claude-Guy},
title = {{Constraint Acquisition Based on Solution Counting}},
booktitle = {28th International Conference on Principles and Practice of Constraint Programming (CP 2022)},
pages = {15:1--15:16},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-240-2},
ISSN = {1868-8969},
year = {2022},
volume = {235},
editor = {Solnon, Christine},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.CP.2022.15},
URN = {urn:nbn:de:0030-drops-166449},
doi = {10.4230/LIPIcs.CP.2022.15},
annote = {Keywords: Constraint acquisition, CSP, Model counting, Solution counting}
}
Document
Computing Relaxations for the Three-Dimensional Stable Matching Problem with Cyclic Preferences
Abstract
Constraint programming has proven to be a successful framework for determining whether a given instance of the three-dimensional stable matching problem with cyclic preferences (3dsm-cyc) admits a solution. If such an instance is satisfiable, constraint models can even compute its optimal solution for several different objective functions. On the other hand, the only existing output for unsatisfiable 3dsm-cyc instances is a simple declaration of impossibility.
In this paper, we explore four ways to adapt constraint models designed for 3dsm-cyc to the maximum relaxation version of the problem, that is, the computation of the smallest part of an instance whose modification leads to satisfiability. We also extend our models to support the presence of costs on elements in the instance, and to return the relaxation with lowest total cost for each of the four types of relaxation. Empirical results reveal that our relaxation models are efficient, as in most cases, they show little overhead compared to the satisfaction version.
Cite as
Ágnes Cseh, Guillaume Escamocher, and Luis Quesada. Computing Relaxations for the Three-Dimensional Stable Matching Problem with Cyclic Preferences. In 28th International Conference on Principles and Practice of Constraint Programming (CP 2022). Leibniz International Proceedings in Informatics (LIPIcs), Volume 235, pp. 16:1-16:19, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2022)
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@InProceedings{cseh_et_al:LIPIcs.CP.2022.16,
author = {Cseh, \'{A}gnes and Escamocher, Guillaume and Quesada, Luis},
title = {{Computing Relaxations for the Three-Dimensional Stable Matching Problem with Cyclic Preferences}},
booktitle = {28th International Conference on Principles and Practice of Constraint Programming (CP 2022)},
pages = {16:1--16:19},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-240-2},
ISSN = {1868-8969},
year = {2022},
volume = {235},
editor = {Solnon, Christine},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.CP.2022.16},
URN = {urn:nbn:de:0030-drops-166450},
doi = {10.4230/LIPIcs.CP.2022.16},
annote = {Keywords: Three-dimensional stable matching with cyclic preferences, 3dsm-cyc, Constraint Programming, relaxation, almost stable matching}
}
Document
DUELMIPs: Optimizing SDN Functionality and Security
Abstract
Software defined networks (SDNs) define a programmable network fabric that can be reconfigured to respect global networks properties. Securing against adversaries who try to exploit the network is an objective that conflicts with providing functionality. This paper proposes a two-stage mixed-integer programming framework. The first stage automates routing decisions for the flows to be carried by the network while maximizing readability and ease of use for network engineers. The second stage is meant to quickly respond to security breaches to automatically decide on network counter-measures to block the detected adversary. Both stages are computationally challenging and the security stage leverages large neighborhood search to quickly deliver effective response strategies. The approach is evaluated on synthetic networks of various sizes and shown to be effective for both its functional and security objectives.
Cite as
Timothy Curry, Gabriel De Pace, Benjamin Fuller, Laurent Michel, and Yan (Lindsay) Sun. DUELMIPs: Optimizing SDN Functionality and Security. In 28th International Conference on Principles and Practice of Constraint Programming (CP 2022). Leibniz International Proceedings in Informatics (LIPIcs), Volume 235, pp. 17:1-17:18, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2022)
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@InProceedings{curry_et_al:LIPIcs.CP.2022.17,
author = {Curry, Timothy and De Pace, Gabriel and Fuller, Benjamin and Michel, Laurent and Sun, Yan (Lindsay)},
title = {{DUELMIPs: Optimizing SDN Functionality and Security}},
booktitle = {28th International Conference on Principles and Practice of Constraint Programming (CP 2022)},
pages = {17:1--17:18},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-240-2},
ISSN = {1868-8969},
year = {2022},
volume = {235},
editor = {Solnon, Christine},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.CP.2022.17},
URN = {urn:nbn:de:0030-drops-166468},
doi = {10.4230/LIPIcs.CP.2022.17},
annote = {Keywords: Network security, mixed integer programming, large neighborhood search}
}
Document
A Framework for Generating Informative Benchmark Instances
Abstract
Benchmarking is an important tool for assessing the relative performance of alternative solving approaches. However, the utility of benchmarking is limited by the quantity and quality of the available problem instances. Modern constraint programming languages typically allow the specification of a class-level model that is parameterised over instance data. This separation presents an opportunity for automated approaches to generate instance data that define instances that are graded (solvable at a certain difficulty level for a solver) or can discriminate between two solving approaches. In this paper, we introduce a framework that combines these two properties to generate a large number of benchmark instances, purposely generated for effective and informative benchmarking. We use five problems that were used in the MiniZinc competition to demonstrate the usage of our framework. In addition to producing a ranking among solvers, our framework gives a broader understanding of the behaviour of each solver for the whole instance space; for example by finding subsets of instances where the solver performance significantly varies from its average performance.
Cite as
Nguyen Dang, Özgür Akgün, Joan Espasa, Ian Miguel, and Peter Nightingale. A Framework for Generating Informative Benchmark Instances. In 28th International Conference on Principles and Practice of Constraint Programming (CP 2022). Leibniz International Proceedings in Informatics (LIPIcs), Volume 235, pp. 18:1-18:18, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2022)
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@InProceedings{dang_et_al:LIPIcs.CP.2022.18,
author = {Dang, Nguyen and Akg\"{u}n, \"{O}zg\"{u}r and Espasa, Joan and Miguel, Ian and Nightingale, Peter},
title = {{A Framework for Generating Informative Benchmark Instances}},
booktitle = {28th International Conference on Principles and Practice of Constraint Programming (CP 2022)},
pages = {18:1--18:18},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-240-2},
ISSN = {1868-8969},
year = {2022},
volume = {235},
editor = {Solnon, Christine},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.CP.2022.18},
URN = {urn:nbn:de:0030-drops-166479},
doi = {10.4230/LIPIcs.CP.2022.18},
annote = {Keywords: Instance generation, Benchmarking, Constraint Programming}
}
Document
Sequence Variables for Routing Problems
Abstract
Constraint Programming (CP) is one of the most flexible approaches for modeling and solving vehicle routing problems (VRP). This paper proposes the sequence variable domain, that is inspired by the insertion graph introduced in [Bent and Van Hentenryck, 2004] and the subset bound domain for set variables. This domain representation, which targets VRP applications, allows for an efficient insertion-based search on a partial tour and the implementation of simple, yet efficient filtering algorithms for constraints that enforce time-windows on the visits and capacities on the vehicles. Experiment results demonstrate the efficiency and flexibility of this CP domain for solving some hard VRP problems, including the Dial-A-Ride, the Patient Transportation, and the asymmetric TSP with time windows.
Cite as
Augustin Delecluse, Pierre Schaus, and Pascal Van Hentenryck. Sequence Variables for Routing Problems. In 28th International Conference on Principles and Practice of Constraint Programming (CP 2022). Leibniz International Proceedings in Informatics (LIPIcs), Volume 235, pp. 19:1-19:17, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2022)
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@InProceedings{delecluse_et_al:LIPIcs.CP.2022.19,
author = {Delecluse, Augustin and Schaus, Pierre and Van Hentenryck, Pascal},
title = {{Sequence Variables for Routing Problems}},
booktitle = {28th International Conference on Principles and Practice of Constraint Programming (CP 2022)},
pages = {19:1--19:17},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-240-2},
ISSN = {1868-8969},
year = {2022},
volume = {235},
editor = {Solnon, Christine},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.CP.2022.19},
URN = {urn:nbn:de:0030-drops-166485},
doi = {10.4230/LIPIcs.CP.2022.19},
annote = {Keywords: Constraint Programming, Dial-A-Ride, Patient Transportation, TSPTW, Vehicle Routing, Sequence Variables, Insertion Variables}
}
Document
CSP Beyond Tractable Constraint Languages
Abstract
The constraint satisfaction problem (CSP) is among the most studied computational problems. While NP-hard, many tractable subproblems have been identified (Bulatov 2017, Zuk 2017). Backdoors, introduced by Williams, Gomes, and Selman (2003), gradually extend such a tractable class to all CSP instances of bounded distance to the class. Backdoor size provides a natural but rather crude distance measure between a CSP instance and a tractable class. Backdoor depth, introduced by Mählmann, Siebertz, and Vigny (2021) for SAT, is a more refined distance measure, which admits the parallel utilization of different backdoor variables. Bounded backdoor size implies bounded backdoor depth, but there are instances of constant backdoor depth and arbitrarily large backdoor size. Dreier, Ordyniak, and Szeider (2022) provided fixed-parameter algorithms for finding backdoors of small depth into the classes of Horn and Krom formulas.
In this paper, we consider backdoor depth for CSP. We consider backdoors w.r.t. tractable subproblems C_Γ of the CSP defined by a constraint language Γ, i.e., where all the constraints use relations from the language Γ. Building upon Dreier et al.’s game-theoretic approach and their notion of separator obstructions, we show that for any finite, tractable, semi-conservative constraint language Γ, the CSP is fixed-parameter tractable parameterized by the backdoor depth into C_Γ plus the domain size.
With backdoors of low depth, we reach classes of instances that require backdoors of arbitrary large size. Hence, our results strictly generalize several known results for CSP that are based on backdoor size.
Cite as
Jan Dreier, Sebastian Ordyniak, and Stefan Szeider. CSP Beyond Tractable Constraint Languages. In 28th International Conference on Principles and Practice of Constraint Programming (CP 2022). Leibniz International Proceedings in Informatics (LIPIcs), Volume 235, pp. 20:1-20:17, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2022)
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@InProceedings{dreier_et_al:LIPIcs.CP.2022.20,
author = {Dreier, Jan and Ordyniak, Sebastian and Szeider, Stefan},
title = {{CSP Beyond Tractable Constraint Languages}},
booktitle = {28th International Conference on Principles and Practice of Constraint Programming (CP 2022)},
pages = {20:1--20:17},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-240-2},
ISSN = {1868-8969},
year = {2022},
volume = {235},
editor = {Solnon, Christine},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.CP.2022.20},
URN = {urn:nbn:de:0030-drops-166490},
doi = {10.4230/LIPIcs.CP.2022.20},
annote = {Keywords: CSP, backdoor depth, constraint language, tractable class, recursive backdoor}
}
Document
Explaining Propagation for Gini and Spread with Variable Mean
Abstract
In optimisation problems involving multiple agents (stakeholders) we often want to make sure that the solution is balanced and fair. That is, we want to maximise total utility subject to an upper bound on the statistical dispersion (e.g., spread or the Gini coefficient) of the utility given to different agents, or minimise dispersion subject to some lower bounds on utility. These needs arise in, for example, balancing tardiness in scheduling, unwanted shifts in rostering, and desired resources in resource allocation, or minimising deviation from a baseline in schedule repair, to name a few. These problems are often quite challenging. To solve them efficiently we want to effectively reason about dispersion. Previous work has studied the case where the mean is fixed, but this may not be possible for many problems, e.g., scheduling where total utility depends on the final schedule. In this paper we introduce two log-linear-time dispersion propagators - (a) spread (variance, and indirectly standard deviation) and (b) the Gini coefficient - capable of explaining their propagations, thus allowing effective clause learning solvers to be applied to these problems. Propagators for (a) exist in the literature but do not explain themselves, while propagators for (b) have not been previously studied. We avoid introducing floating-point variables, which are usually not supported by learning solvers, by reasoning about scaled, integer versions of the constraints. We show through experimentation that clause learning can substantially improve the solving of problems where we want to bound dispersion and optimise total utility and vice versa.
Cite as
Alexander Ek, Andreas Schutt, Peter J. Stuckey, and Guido Tack. Explaining Propagation for Gini and Spread with Variable Mean. In 28th International Conference on Principles and Practice of Constraint Programming (CP 2022). Leibniz International Proceedings in Informatics (LIPIcs), Volume 235, pp. 21:1-21:16, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2022)
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@InProceedings{ek_et_al:LIPIcs.CP.2022.21,
author = {Ek, Alexander and Schutt, Andreas and Stuckey, Peter J. and Tack, Guido},
title = {{Explaining Propagation for Gini and Spread with Variable Mean}},
booktitle = {28th International Conference on Principles and Practice of Constraint Programming (CP 2022)},
pages = {21:1--21:16},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-240-2},
ISSN = {1868-8969},
year = {2022},
volume = {235},
editor = {Solnon, Christine},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.CP.2022.21},
URN = {urn:nbn:de:0030-drops-166503},
doi = {10.4230/LIPIcs.CP.2022.21},
annote = {Keywords: Spread constraint, Gini index, Filtering algorithm, Constraint programming, Lazy clause generation}
}
Document
Plotting: A Planning Problem with Complex Transitions
Abstract
We focus on a planning problem based on Plotting, a tile-matching puzzle video game published by Taito. The objective of the game is to remove at least a certain number of coloured blocks from a grid by sequentially shooting blocks into the same grid. The interest and difficulty of Plotting is due to the complex transitions after every shot: various blocks are affected directly, while others can be indirectly affected by gravity. We highlight the difficulties and inefficiencies of modelling and solving Plotting using PDDL, the de-facto standard language for AI planners. We also provide two constraint models that are able to capture the inherent complexities of the problem. In addition, we provide a set of benchmark instances, an instance generator and an extensive experimental comparison demonstrating solving performance with SAT, CP, MIP and a state-of-the-art AI planner.
Cite as
Joan Espasa, Ian Miguel, and Mateu Villaret. Plotting: A Planning Problem with Complex Transitions. In 28th International Conference on Principles and Practice of Constraint Programming (CP 2022). Leibniz International Proceedings in Informatics (LIPIcs), Volume 235, pp. 22:1-22:17, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2022)
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@InProceedings{espasa_et_al:LIPIcs.CP.2022.22,
author = {Espasa, Joan and Miguel, Ian and Villaret, Mateu},
title = {{Plotting: A Planning Problem with Complex Transitions}},
booktitle = {28th International Conference on Principles and Practice of Constraint Programming (CP 2022)},
pages = {22:1--22:17},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-240-2},
ISSN = {1868-8969},
year = {2022},
volume = {235},
editor = {Solnon, Christine},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.CP.2022.22},
URN = {urn:nbn:de:0030-drops-166514},
doi = {10.4230/LIPIcs.CP.2022.22},
annote = {Keywords: AI Planning, Modelling, Constraint Programming}
}
Document
Nucleus-Satellites Systems of OMDDs for Reducing the Size of Compiled Forms
Abstract
In order to reduce the size of compiled forms in knowledge compilation, we propose a new approach based on a splitting of the main representation into a nucleus representation and satellite representations. Nucleus representation is the projection of the original representation onto the "main" variables and satellite representations define the other variables according to the nucleus. We propose a language and a method, aimed at OBDD/OMDD representations, to compile into this split form. Our experimental study shows major size reductions on configuration- and diagnosis- oriented benchmarks.
Cite as
Hélène Fargier, Jérôme Mengin, and Nicolas Schmidt. Nucleus-Satellites Systems of OMDDs for Reducing the Size of Compiled Forms. In 28th International Conference on Principles and Practice of Constraint Programming (CP 2022). Leibniz International Proceedings in Informatics (LIPIcs), Volume 235, pp. 23:1-23:18, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2022)
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@InProceedings{fargier_et_al:LIPIcs.CP.2022.23,
author = {Fargier, H\'{e}l\`{e}ne and Mengin, J\'{e}r\^{o}me and Schmidt, Nicolas},
title = {{Nucleus-Satellites Systems of OMDDs for Reducing the Size of Compiled Forms}},
booktitle = {28th International Conference on Principles and Practice of Constraint Programming (CP 2022)},
pages = {23:1--23:18},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-240-2},
ISSN = {1868-8969},
year = {2022},
volume = {235},
editor = {Solnon, Christine},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.CP.2022.23},
URN = {urn:nbn:de:0030-drops-166521},
doi = {10.4230/LIPIcs.CP.2022.23},
annote = {Keywords: Knowledge representation, knowledge compilation, ordered multivalued decision diagram}
}
Document
Heuristics for MDD Propagation in HADDOCK
Abstract
Haddock, introduced in [R. Gentzel et al., 2020], is a declarative language and architecture for the specification and the implementation of multi-valued decision diagrams. It relies on a labeled transition system to specify and compose individual constraints into a propagator with filtering capabilities that automatically deliver the expected level of filtering. Yet, the operational potency of the filtering algorithms strongly correlate with heuristics for carrying out refinements of the diagrams. This paper considers how to empower Haddock users with the ability to unobtrusively specify various such heuristics and derive the computational benefits of exerting fine-grained control over the refinement process.
Cite as
Rebecca Gentzel, Laurent Michel, and Willem-Jan van Hoeve. Heuristics for MDD Propagation in HADDOCK. In 28th International Conference on Principles and Practice of Constraint Programming (CP 2022). Leibniz International Proceedings in Informatics (LIPIcs), Volume 235, pp. 24:1-24:17, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2022)
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@InProceedings{gentzel_et_al:LIPIcs.CP.2022.24,
author = {Gentzel, Rebecca and Michel, Laurent and van Hoeve, Willem-Jan},
title = {{Heuristics for MDD Propagation in HADDOCK}},
booktitle = {28th International Conference on Principles and Practice of Constraint Programming (CP 2022)},
pages = {24:1--24:17},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-240-2},
ISSN = {1868-8969},
year = {2022},
volume = {235},
editor = {Solnon, Christine},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.CP.2022.24},
URN = {urn:nbn:de:0030-drops-166534},
doi = {10.4230/LIPIcs.CP.2022.24},
annote = {Keywords: Decision Diagrams}
}
Document
An Auditable Constraint Programming Solver
Abstract
We describe the design and implementation of a new constraint programming solver that can produce an auditable record of what problem was solved and how the solution was reached. As well as a solution, this solver provides an independently verifiable proof log demonstrating that the solution is correct. This proof log uses the VeriPB proof system, which is based upon cutting planes reasoning with extension variables. We explain how this system can support global constraints, variables with large domains, and reformulation, despite not natively understanding any of these concepts.
Cite as
Stephan Gocht, Ciaran McCreesh, and Jakob Nordström. An Auditable Constraint Programming Solver. In 28th International Conference on Principles and Practice of Constraint Programming (CP 2022). Leibniz International Proceedings in Informatics (LIPIcs), Volume 235, pp. 25:1-25:18, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2022)
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@InProceedings{gocht_et_al:LIPIcs.CP.2022.25,
author = {Gocht, Stephan and McCreesh, Ciaran and Nordstr\"{o}m, Jakob},
title = {{An Auditable Constraint Programming Solver}},
booktitle = {28th International Conference on Principles and Practice of Constraint Programming (CP 2022)},
pages = {25:1--25:18},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-240-2},
ISSN = {1868-8969},
year = {2022},
volume = {235},
editor = {Solnon, Christine},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.CP.2022.25},
URN = {urn:nbn:de:0030-drops-166548},
doi = {10.4230/LIPIcs.CP.2022.25},
annote = {Keywords: Constraint programming, proof logging, auditable solving}
}
Document
From Cliques to Colorings and Back Again
Abstract
We present an exact algorithm for graph coloring and maximum clique problems based on SAT technology. It relies on four sub-algorithms that alternatingly compute cliques of larger size and colorings with fewer colors. We show how these techniques can mutually help each other: larger cliques facilitate finding smaller colorings, which in turn can boost finding larger cliques. We evaluate our approach on the DIMACS graph coloring suite. For finding maximum cliques, we show that our algorithm can improve the state-of-the-art MaxSAT-based solver IncMaxCLQ, and for the graph coloring problem, we close two open instances, decrease two upper bounds, and increase one lower bound.
Cite as
Marijn J. H. Heule, Anthony Karahalios, and Willem-Jan van Hoeve. From Cliques to Colorings and Back Again. In 28th International Conference on Principles and Practice of Constraint Programming (CP 2022). Leibniz International Proceedings in Informatics (LIPIcs), Volume 235, pp. 26:1-26:10, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2022)
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@InProceedings{heule_et_al:LIPIcs.CP.2022.26,
author = {Heule, Marijn J. H. and Karahalios, Anthony and van Hoeve, Willem-Jan},
title = {{From Cliques to Colorings and Back Again}},
booktitle = {28th International Conference on Principles and Practice of Constraint Programming (CP 2022)},
pages = {26:1--26:10},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-240-2},
ISSN = {1868-8969},
year = {2022},
volume = {235},
editor = {Solnon, Christine},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.CP.2022.26},
URN = {urn:nbn:de:0030-drops-166558},
doi = {10.4230/LIPIcs.CP.2022.26},
annote = {Keywords: Graph coloring, maximum clique, Boolean satisfiability}
}
Document
On the Enumeration of Frequent High Utility Itemsets: A Symbolic AI Approach
Abstract
Mining interesting patterns from data is a core part of the data mining world. High utility mining, an active research topic in data mining, aims to discover valuable itemsets with high profit (e.g., cost, risk). However, the measure of interest of an itemset must primarily reflect not only the importance of items in terms of profit, but also their occurrence in data in order to make more crucial decisions. Some proposals are then introduced to deal with the problem of computing high utility itemsets that meet a minimum support threshold. However, in these existing proposals, all transactions in which the itemset appears are taken into account, including those in which the itemset has a low profit. So, no additional information about the overall utility of the itemset is taken into account. This paper addresses this issue by introducing a SAT-based model to efficiently find the set of all frequent high utility itemsets with the use of a minimum utility threshold applied to each transaction in which the itemset appears. More specifically, we reduce the problem of mining frequent high utility itemsets to the one of enumerating the models of a formula in propositional logic, and then we use state-of-the-art SAT solvers to solve it. Afterwards, to make our approach more efficient, we provide a decomposition technique that is particularly suitable for deriving smaller and independent sub-problems easy to resolve. Finally, an extensive experimental evaluation on various popular datasets shows that our method is fast and scale well compared to the state-of-the art algorithms.
Cite as
Amel Hidouri, Said Jabbour, and Badran Raddaoui. On the Enumeration of Frequent High Utility Itemsets: A Symbolic AI Approach. In 28th International Conference on Principles and Practice of Constraint Programming (CP 2022). Leibniz International Proceedings in Informatics (LIPIcs), Volume 235, pp. 27:1-27:17, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2022)
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@InProceedings{hidouri_et_al:LIPIcs.CP.2022.27,
author = {Hidouri, Amel and Jabbour, Said and Raddaoui, Badran},
title = {{On the Enumeration of Frequent High Utility Itemsets: A Symbolic AI Approach}},
booktitle = {28th International Conference on Principles and Practice of Constraint Programming (CP 2022)},
pages = {27:1--27:17},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-240-2},
ISSN = {1868-8969},
year = {2022},
volume = {235},
editor = {Solnon, Christine},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.CP.2022.27},
URN = {urn:nbn:de:0030-drops-166564},
doi = {10.4230/LIPIcs.CP.2022.27},
annote = {Keywords: Data Mining, High Utility Itemsets, Propositional Satisfiability}
}
Document
Understanding How People Approach Constraint Modelling and Solving
Abstract
Research in constraint programming typically focuses on problem solving efficiency. However, the way users conceptualise problems and communicate with constraint programming tools is often sidelined. How humans think about constraint problems can be important for the development of efficient tools that are useful to a broader audience. For example, a system incorporating knowledge on how people think about constraint problems can provide explanations to users and improve the communication between the human and the solver.
We present an initial step towards a better understanding of the human side of the constraint solving process. To our knowledge, this is the first human-centred study addressing how people approach constraint modelling and solving. We observed three sets of ten users each (constraint programmers, computer scientists and non-computer scientists) and analysed how they find solutions for well-known constraint problems. We found regularities offering clues about how to design systems that are more intelligible to humans.
Cite as
Ruth Hoffmann, Xu Zhu, Özgür Akgün, and Miguel A. Nacenta. Understanding How People Approach Constraint Modelling and Solving. In 28th International Conference on Principles and Practice of Constraint Programming (CP 2022). Leibniz International Proceedings in Informatics (LIPIcs), Volume 235, pp. 28:1-28:18, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2022)
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@InProceedings{hoffmann_et_al:LIPIcs.CP.2022.28,
author = {Hoffmann, Ruth and Zhu, Xu and Akg\"{u}n, \"{O}zg\"{u}r and Nacenta, Miguel A.},
title = {{Understanding How People Approach Constraint Modelling and Solving}},
booktitle = {28th International Conference on Principles and Practice of Constraint Programming (CP 2022)},
pages = {28:1--28:18},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-240-2},
ISSN = {1868-8969},
year = {2022},
volume = {235},
editor = {Solnon, Christine},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.CP.2022.28},
URN = {urn:nbn:de:0030-drops-166574},
doi = {10.4230/LIPIcs.CP.2022.28},
annote = {Keywords: Constraint Modelling, HCI, User Study, Grounded Theory}
}
Document
Learning Constraint Programming Models from Data Using Generate-And-Aggregate
Abstract
Constraint programming (CP) is used widely for solving real-world problems. However, designing these models require substantial expertise. In this paper, we tackle this problem by synthesizing models automatically from past solutions. We introduce COUNT-CP, which uses simple grammars and a generate-and-aggregate approach to learn expressive first-order constraints typically used in CP as well as their parameters from data. The learned constraints generalize across instances over different sizes and can be used to solve unseen instances - e.g., learning constraints from a 4×4 Sudoku to solve a 9×9 Sudoku or learning nurse staffing requirements across hospitals. COUNT-CP is implemented using the CPMpy constraint programming and modelling environment to produce constraints with nested mathematical expressions. The method is empirically evaluated on a set of suitable benchmark problems and shows to learn accurate and compact models quickly.
Cite as
Mohit Kumar, Samuel Kolb, and Tias Guns. Learning Constraint Programming Models from Data Using Generate-And-Aggregate. In 28th International Conference on Principles and Practice of Constraint Programming (CP 2022). Leibniz International Proceedings in Informatics (LIPIcs), Volume 235, pp. 29:1-29:16, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2022)
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@InProceedings{kumar_et_al:LIPIcs.CP.2022.29,
author = {Kumar, Mohit and Kolb, Samuel and Guns, Tias},
title = {{Learning Constraint Programming Models from Data Using Generate-And-Aggregate}},
booktitle = {28th International Conference on Principles and Practice of Constraint Programming (CP 2022)},
pages = {29:1--29:16},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-240-2},
ISSN = {1868-8969},
year = {2022},
volume = {235},
editor = {Solnon, Christine},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.CP.2022.29},
URN = {urn:nbn:de:0030-drops-166580},
doi = {10.4230/LIPIcs.CP.2022.29},
annote = {Keywords: Constraint Learning, Constraint Programming, Model Synthesis}
}
Document
Combining Reinforcement Learning and Constraint Programming for Sequence-Generation Tasks with Hard Constraints
Abstract
While Machine Learning (ML) techniques are good at generating data similar to a dataset, they lack the capacity to enforce constraints. On the other hand, any solution to a Constraint Programming (CP) model satisfies its constraints but has no obligation to imitate a dataset. Yet, we sometimes need both. In this paper we borrow RL-Tuner, a Reinforcement Learning (RL) algorithm introduced to tune neural networks, as our enabling architecture to exploit the respective strengths of ML and CP. RL-Tuner maximizes the sum of a pretrained network’s learned probabilities and of manually-tuned penalties for each violated constraint. We replace the latter with outputs of a CP model representing the marginal probabilities of each value and the number of constraint violations. As was the case for the original RL-Tuner, we apply our algorithm to music generation since it is a highly-constrained domain for which CP is especially suited. We show that combining ML and CP, as opposed to using them individually, allows the agent to reflect the pretrained network while taking into account constraints, leading to melodic lines that respect both the corpus' style and the music theory constraints.
Cite as
Daphné Lafleur, Sarath Chandar, and Gilles Pesant. Combining Reinforcement Learning and Constraint Programming for Sequence-Generation Tasks with Hard Constraints. In 28th International Conference on Principles and Practice of Constraint Programming (CP 2022). Leibniz International Proceedings in Informatics (LIPIcs), Volume 235, pp. 30:1-30:16, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2022)
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@InProceedings{lafleur_et_al:LIPIcs.CP.2022.30,
author = {Lafleur, Daphn\'{e} and Chandar, Sarath and Pesant, Gilles},
title = {{Combining Reinforcement Learning and Constraint Programming for Sequence-Generation Tasks with Hard Constraints}},
booktitle = {28th International Conference on Principles and Practice of Constraint Programming (CP 2022)},
pages = {30:1--30:16},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-240-2},
ISSN = {1868-8969},
year = {2022},
volume = {235},
editor = {Solnon, Christine},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.CP.2022.30},
URN = {urn:nbn:de:0030-drops-166594},
doi = {10.4230/LIPIcs.CP.2022.30},
annote = {Keywords: Constraint programming, reinforcement learning, RNN, music generation}
}
Document
Exploiting Functional Constraints in Automatic Dominance Breaking for Constraint Optimization
Abstract
Dominance breaking is an effective technique to reduce the time for solving constraint optimization problems. Lee and Zhong propose an automatic dominance breaking framework for a class of constraint optimization problems based on specific forms of objectives and constraints. In this paper, we propose to enhance the framework for problems with nested function calls which can be flattened to functional constraints. In particular, we focus on aggregation functions and exploit such properties as monotonicity, commutativity and associativity to give an efficient procedure for generating effective dominance breaking nogoods. Experimentation also shows orders-of-magnitude runtime speedup using the generated dominance breaking nogoods and demonstrates the ability of our proposal to reveal dominance relations in the literature and discover new dominance relations on problems with ineffective or no known dominance breaking constraints.
Cite as
Jimmy H. M. Lee and Allen Z. Zhong. Exploiting Functional Constraints in Automatic Dominance Breaking for Constraint Optimization. In 28th International Conference on Principles and Practice of Constraint Programming (CP 2022). Leibniz International Proceedings in Informatics (LIPIcs), Volume 235, pp. 31:1-31:17, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2022)
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@InProceedings{lee_et_al:LIPIcs.CP.2022.31,
author = {Lee, Jimmy H. M. and Zhong, Allen Z.},
title = {{Exploiting Functional Constraints in Automatic Dominance Breaking for Constraint Optimization}},
booktitle = {28th International Conference on Principles and Practice of Constraint Programming (CP 2022)},
pages = {31:1--31:17},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-240-2},
ISSN = {1868-8969},
year = {2022},
volume = {235},
editor = {Solnon, Christine},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.CP.2022.31},
URN = {urn:nbn:de:0030-drops-166607},
doi = {10.4230/LIPIcs.CP.2022.31},
annote = {Keywords: Constraint Optimization Problems, Dominance Breaking}
}
Document
A Portfolio-Based Approach to Select Efficient Variable Ordering Heuristics for Constraint Satisfaction Problems
Abstract
Variable ordering heuristics (VOH) play a central role in solving Constraint Satisfaction Problems (CSP). The performance of different VOHs may vary greatly in solving the same CSP instance. In this paper, we propose an approach to select efficient VOHs for solving different CSP instances. The approach contains two phases. The first phase is a probing procedure that runs a simple portfolio strategy containing several different VOHs. The portfolio tries to use each of the candidate VOHs to guide backtracking search to solve the CSP instance within a limited number of failures. If the CSP is not solved by the portfolio, one of the candidates is selected for it by analysing the information attached in the search trees generated by the candidates. The second phase uses the selected VOH to guide backtracking search to solve the CSP. The experiments are run with the MiniZinc benchmark suite and four different VOHs which are considered as the state of the art are involved. The results show that the proposed approach finds the best VOH for more than 67% instances and it solves more instances than all the candidate VOHs and an adaptive VOH based on Multi-Armed Bandit. It could be an effective adaptive search strategy for black-box CSP solvers.
Cite as
Hongbo Li, Yaling Wu, Minghao Yin, and Zhanshan Li. A Portfolio-Based Approach to Select Efficient Variable Ordering Heuristics for Constraint Satisfaction Problems. In 28th International Conference on Principles and Practice of Constraint Programming (CP 2022). Leibniz International Proceedings in Informatics (LIPIcs), Volume 235, pp. 32:1-32:10, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2022)
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@InProceedings{li_et_al:LIPIcs.CP.2022.32,
author = {Li, Hongbo and Wu, Yaling and Yin, Minghao and Li, Zhanshan},
title = {{A Portfolio-Based Approach to Select Efficient Variable Ordering Heuristics for Constraint Satisfaction Problems}},
booktitle = {28th International Conference on Principles and Practice of Constraint Programming (CP 2022)},
pages = {32:1--32:10},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-240-2},
ISSN = {1868-8969},
year = {2022},
volume = {235},
editor = {Solnon, Christine},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.CP.2022.32},
URN = {urn:nbn:de:0030-drops-166616},
doi = {10.4230/LIPIcs.CP.2022.32},
annote = {Keywords: Constraint Satisfaction Problem, Variable Ordering Heuristic, Adaptive Search Heuristic, Portfolio}
}
Document
Large Neighborhood Search for Robust Solutions for Constraint Satisfaction Problems with Ordered Domains
Abstract
Often, real-world Constraint Satisfaction Problems (CSPs) are subject to uncertainty/dynamism not known in advance. Some techniques in the literature offer robust solutions for CSPs. Here, we analyze a previous exact/complete approach from the state-of-the-art that focuses on CSPs with ordered domains and dynamic bounds. However, this approach has low performance in large-scale CSPs. For this reason, in this paper, we present an inexact/incomplete approach that is faster at finding robust solutions for large-scale CSPs. It is useful when the computation time available for finding a solution is limited and/or in situations where a new one must be re-computed online because the dynamism invalidated the original one. Specifically, we present a Large Neighbourhood Search (LNS) algorithm combined with Constraint Programming (CP) and Branch-and-bound (B&B) that searches for robust solutions. We also present a robust-value selection heuristic that guides the search toward more promising branches. We evaluate our approach with large-scale CSPs instances, including the case study of scheduling problems. The evaluation shows a considerable improvement in the robustness of the solutions achieved by our algorithm for large-scale CSPs.
Cite as
Jheisson López, Alejandro Arbelaez, and Laura Climent. Large Neighborhood Search for Robust Solutions for Constraint Satisfaction Problems with Ordered Domains. In 28th International Conference on Principles and Practice of Constraint Programming (CP 2022). Leibniz International Proceedings in Informatics (LIPIcs), Volume 235, pp. 33:1-33:16, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2022)
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@InProceedings{lopez_et_al:LIPIcs.CP.2022.33,
author = {L\'{o}pez, Jheisson and Arbelaez, Alejandro and Climent, Laura},
title = {{Large Neighborhood Search for Robust Solutions for Constraint Satisfaction Problems with Ordered Domains}},
booktitle = {28th International Conference on Principles and Practice of Constraint Programming (CP 2022)},
pages = {33:1--33:16},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-240-2},
ISSN = {1868-8969},
year = {2022},
volume = {235},
editor = {Solnon, Christine},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.CP.2022.33},
URN = {urn:nbn:de:0030-drops-166625},
doi = {10.4230/LIPIcs.CP.2022.33},
annote = {Keywords: Constraint Programming, Large Neighbourhood Search, Robust Solutions}
}
Document
Scheduling the Equipment Maintenance of an Electric Power Transmission Network Using Constraint Programming
Abstract
Modern electrical power utilities must maintain their electrical equipment and replace it when the end of its useful life arrives. The Transmission Maintenance Scheduling (TMS) problem consists in generating an annual maintenance plan for electric power transportation equipment while maintaining the stability of the network and ensuring a continuous power flow for customers. Each year, a list of equipment (power lines, capacitors, transistors, etc.) that needs to be maintained or replaced is available and the goal is to generate an optimal maintenance plan. This paper proposes a constraint-based scheduling approach for solving the TMS problem. The model considers two types of constraints: (1) constraints that can be naturally formalized inside a constraint programming model, and (2) complex constraints that do not have a proper formalization from the field specialists. The latter cannot be integrated inside the model due to their complexity. Their satisfaction is thus verified by a black box tool, which is a simulator that mimics the impact of a maintenance schedule on the real power network. The simulator is based on complex differential power-flow equations. Experiments are carried out at five strategic points of Hydro-Québec power grid infrastructure, and involve more than 200 electrical equipment and 300 withdrawal requests. Results show that the model is able to comply with most of the formalized and unformalized constraints. It also generates maintenance schedules within an execution time of only a few minutes. The generated schedules are similar to the ones proposed by a field specialist and can be used to simulate maintenance programs for the next 10 years.
Cite as
Louis Popovic, Alain Côté, Mohamed Gaha, Franklin Nguewouo, and Quentin Cappart. Scheduling the Equipment Maintenance of an Electric Power Transmission Network Using Constraint Programming. In 28th International Conference on Principles and Practice of Constraint Programming (CP 2022). Leibniz International Proceedings in Informatics (LIPIcs), Volume 235, pp. 34:1-34:15, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2022)
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@InProceedings{popovic_et_al:LIPIcs.CP.2022.34,
author = {Popovic, Louis and C\^{o}t\'{e}, Alain and Gaha, Mohamed and Nguewouo, Franklin and Cappart, Quentin},
title = {{Scheduling the Equipment Maintenance of an Electric Power Transmission Network Using Constraint Programming}},
booktitle = {28th International Conference on Principles and Practice of Constraint Programming (CP 2022)},
pages = {34:1--34:15},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-240-2},
ISSN = {1868-8969},
year = {2022},
volume = {235},
editor = {Solnon, Christine},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.CP.2022.34},
URN = {urn:nbn:de:0030-drops-166635},
doi = {10.4230/LIPIcs.CP.2022.34},
annote = {Keywords: Transmission maintenance scheduling, Electric power network, Constraint programming}
}
Document
Peel-And-Bound: Generating Stronger Relaxed Bounds with Multivalued Decision Diagrams
Abstract
Decision diagrams are an increasingly important tool in cutting-edge solvers for discrete optimization. However, the field of decision diagrams is relatively new, and is still incorporating the library of techniques that conventional solvers have had decades to build. We drew inspiration from the warm-start technique used in conventional solvers to address one of the major challenges faced by decision diagram based methods. Decision diagrams become more useful the wider they are allowed to be, but also become more costly to generate, especially with large numbers of variables. We present a method of peeling off a sub-graph of previously constructed diagrams and using it as the initial diagram for subsequent iterations that we call peel-and-bound. We test the method on the sequence ordering problem, and our results indicate that our peel-and-bound scheme generates stronger bounds than a branch-and-bound scheme using the same propagators, and at significantly less computational cost.
Cite as
Isaac Rudich, Quentin Cappart, and Louis-Martin Rousseau. Peel-And-Bound: Generating Stronger Relaxed Bounds with Multivalued Decision Diagrams. In 28th International Conference on Principles and Practice of Constraint Programming (CP 2022). Leibniz International Proceedings in Informatics (LIPIcs), Volume 235, pp. 35:1-35:20, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2022)
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@InProceedings{rudich_et_al:LIPIcs.CP.2022.35,
author = {Rudich, Isaac and Cappart, Quentin and Rousseau, Louis-Martin},
title = {{Peel-And-Bound: Generating Stronger Relaxed Bounds with Multivalued Decision Diagrams}},
booktitle = {28th International Conference on Principles and Practice of Constraint Programming (CP 2022)},
pages = {35:1--35:20},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-240-2},
ISSN = {1868-8969},
year = {2022},
volume = {235},
editor = {Solnon, Christine},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.CP.2022.35},
URN = {urn:nbn:de:0030-drops-166647},
doi = {10.4230/LIPIcs.CP.2022.35},
annote = {Keywords: decision diagrams, discrete optimization, branch-and-bound, sequencing, constraint programming}
}
Document
On Quantitative Testing of Samplers
Abstract
The problem of uniform sampling is, given a formula F, sample solutions of F uniformly at random from the solution space of F. Uniform sampling is a fundamental problem with widespread applications, including configuration testing, bug synthesis, function synthesis, and many more. State-of-the-art approaches for uniform sampling have a trade-off between scalability and theoretical guarantees. Many state of the art uniform samplers do not provide any theoretical guarantees on the distribution of samples generated, however, empirically they have shown promising results. In such cases, the main challenge is to test whether the distribution according to which samples are generated is indeed uniform or not.
Recently, Chakraborty and Meel (2019) designed the first scalable sampling tester, Barbarik, based on a grey-box sampling technique for testing if the distribution, according to which the given sampler is sampling, is close to the uniform or far from uniform. They were able to show that many off-the-self samplers are far from a uniform sampler. The availability of Barbarik increased the test-driven development of samplers. More recently, Golia, Soos, Chakraborty and Meel (2021), designed a uniform like sampler, CMSGen, which was shown to be accepted by Barbarik on all the instances. However, CMSGen does not provide any theoretical analysis of the sampling quality.
CMSGen leads us to observe the need for a tester to provide a quantitative answer to determine the quality of underlying samplers instead of merely a qualitative answer of Accept or Reject. Towards this goal, we design a computational hardness-based tester ScalBarbarik that provides a more nuanced analysis of the quality of a sampler. ScalBarbarik allows more expressive measurement of the quality of the underlying samplers. We empirically show that the state-of-the-art sampler, CMSGen is not accepted as a uniform-like sampler by ScalBarbarik. Furthermore, we show that ScalBarbarik can be used to design a sampler that can achieve balance between scalability and uniformity.
Cite as
Mate Soos, Priyanka Golia, Sourav Chakraborty, and Kuldeep S. Meel. On Quantitative Testing of Samplers. In 28th International Conference on Principles and Practice of Constraint Programming (CP 2022). Leibniz International Proceedings in Informatics (LIPIcs), Volume 235, pp. 36:1-36:16, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2022)
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@InProceedings{soos_et_al:LIPIcs.CP.2022.36,
author = {Soos, Mate and Golia, Priyanka and Chakraborty, Sourav and Meel, Kuldeep S.},
title = {{On Quantitative Testing of Samplers}},
booktitle = {28th International Conference on Principles and Practice of Constraint Programming (CP 2022)},
pages = {36:1--36:16},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-240-2},
ISSN = {1868-8969},
year = {2022},
volume = {235},
editor = {Solnon, Christine},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.CP.2022.36},
URN = {urn:nbn:de:0030-drops-166655},
doi = {10.4230/LIPIcs.CP.2022.36},
annote = {Keywords: SAT Sampling, Testing of Samplers, SAT Solvers}
}
Document
Structured Set Variable Domains in Bayesian Network Structure Learning
Abstract
Constraint programming is a state of the art technique for learning the structure of Bayesian Networks from data (Bayesian Network Structure Learning - BNSL). However, scalability both for CP and other combinatorial optimization techniques for this problem is limited by the fact that the basic decision variables are set variables with domain sizes that may grow super polynomially with the number of random variables. Usual techniques for handling set variables in CP are not useful, as they lead to poor bounds. In this paper, we propose using decision trees as a data structure for storing sets of sets to represent set variable domains. We show that relatively simple operations are sufficient to implement all propagation and bounding algorithms, and that the use of these data structures improves scalability of a state of the art CP-based solver for BNSL.
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Fulya Trösser, Simon de Givry, and George Katsirelos. Structured Set Variable Domains in Bayesian Network Structure Learning. In 28th International Conference on Principles and Practice of Constraint Programming (CP 2022). Leibniz International Proceedings in Informatics (LIPIcs), Volume 235, pp. 37:1-37:9, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2022)
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@InProceedings{trosser_et_al:LIPIcs.CP.2022.37,
author = {Tr\"{o}sser, Fulya and de Givry, Simon and Katsirelos, George},
title = {{Structured Set Variable Domains in Bayesian Network Structure Learning}},
booktitle = {28th International Conference on Principles and Practice of Constraint Programming (CP 2022)},
pages = {37:1--37:9},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-240-2},
ISSN = {1868-8969},
year = {2022},
volume = {235},
editor = {Solnon, Christine},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.CP.2022.37},
URN = {urn:nbn:de:0030-drops-166661},
doi = {10.4230/LIPIcs.CP.2022.37},
annote = {Keywords: Combinatorial Optimization, Bayesian Networks, Decision Trees}
}
Document
Selecting SAT Encodings for Pseudo-Boolean and Linear Integer Constraints
Abstract
Many constraint satisfaction and optimisation problems can be solved effectively by encoding them as instances of the Boolean Satisfiability problem (SAT). However, even the simplest types of constraints have many encodings in the literature with widely varying performance, and the problem of selecting suitable encodings for a given problem instance is not trivial. We explore the problem of selecting encodings for pseudo-Boolean and linear constraints using a supervised machine learning approach. We show that it is possible to select encodings effectively using a standard set of features for constraint problems; however we obtain better performance with a new set of features specifically designed for the pseudo-Boolean and linear constraints. In fact, we achieve good results when selecting encodings for unseen problem classes. Our results compare favourably to AutoFolio when using the same feature set. We discuss the relative importance of instance features to the task of selecting the best encodings, and compare several variations of the machine learning method.
Cite as
Felix Ulrich-Oltean, Peter Nightingale, and James Alfred Walker. Selecting SAT Encodings for Pseudo-Boolean and Linear Integer Constraints. In 28th International Conference on Principles and Practice of Constraint Programming (CP 2022). Leibniz International Proceedings in Informatics (LIPIcs), Volume 235, pp. 38:1-38:17, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2022)
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@InProceedings{ulricholtean_et_al:LIPIcs.CP.2022.38,
author = {Ulrich-Oltean, Felix and Nightingale, Peter and Walker, James Alfred},
title = {{Selecting SAT Encodings for Pseudo-Boolean and Linear Integer Constraints}},
booktitle = {28th International Conference on Principles and Practice of Constraint Programming (CP 2022)},
pages = {38:1--38:17},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-240-2},
ISSN = {1868-8969},
year = {2022},
volume = {235},
editor = {Solnon, Christine},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.CP.2022.38},
URN = {urn:nbn:de:0030-drops-166670},
doi = {10.4230/LIPIcs.CP.2022.38},
annote = {Keywords: Constraint programming, SAT encodings, machine learning, global constraints, pseudo-Boolean constraints, linear constraints}
}
Document
Completeness Matters: Towards Efficient Caching in Tree-Based Synchronous Backtracking Search for DCOPs
Abstract
Tree-based backtracking search is an important technique to solve Distributed Constraint optimization Problems (DCOPs), where agents cooperatively exhaust the search space by branching on each variable to divide subproblems and reporting the results to their parent after solving each subproblem. Therefore, effectively reusing the historical search results can avoid unnecessary resolutions and substantially reduce the overall overhead. However, the existing caching schemes for asynchronous algorithms cannot be applied directly to synchronous ones, in the sense that child agent reports the lower and upper bound rather than the precise cost of exploration. In addition, the existing caching scheme for synchronous algorithms has the shortcomings of incompleteness and low cache utilization. Therefore, we propose a new caching scheme for tree-based synchronous backtracking search, named Retention Scheme (RS). It utilizes the upper bounds of subproblems which avoid the reuse of suboptimal solutions to ensure the completeness, and deploys a fine-grained cache information unit targeted at each child agent to improve the cache-hit rate. Furthermore, we introduce two new cache replacement schemes to further improve performance when the memory is limited. Finally, we theoretically prove the completeness of our method and empirically show its superiority.
Cite as
Jie Wang, Dingding Chen, Ziyu Chen, Xiangshuang Liu, and Junsong Gao. Completeness Matters: Towards Efficient Caching in Tree-Based Synchronous Backtracking Search for DCOPs. In 28th International Conference on Principles and Practice of Constraint Programming (CP 2022). Leibniz International Proceedings in Informatics (LIPIcs), Volume 235, pp. 39:1-39:17, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2022)
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@InProceedings{wang_et_al:LIPIcs.CP.2022.39,
author = {Wang, Jie and Chen, Dingding and Chen, Ziyu and Liu, Xiangshuang and Gao, Junsong},
title = {{Completeness Matters: Towards Efficient Caching in Tree-Based Synchronous Backtracking Search for DCOPs}},
booktitle = {28th International Conference on Principles and Practice of Constraint Programming (CP 2022)},
pages = {39:1--39:17},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-240-2},
ISSN = {1868-8969},
year = {2022},
volume = {235},
editor = {Solnon, Christine},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.CP.2022.39},
URN = {urn:nbn:de:0030-drops-166685},
doi = {10.4230/LIPIcs.CP.2022.39},
annote = {Keywords: DCOP, Cache, Any-space Algorithms, Complete Search Algorithms}
}
Document
CNF Encodings of Binary Constraint Trees
Abstract
Ordered Multi-valued Decision Diagrams (MDDs) have been shown to be useful to represent finite domain functions/relations. For example, various constraints can be modelled with MDD constraints. Recently, a new representation called Binary Constraint Tree (BCT), which is a (special) tree structure binary Constraint Satisfaction Problem, has been proposed to encode MDDs and shown to outperform existing MDD constraint propagators in Constraint Programming solvers. BCT is a compact representation, and it can be exponentially smaller than MDD for representing some constraints. Here, we also show that BCT is compact for representing non-deterministic finite state automaton (NFA) constraints. In this paper, we investigate how to encode BCT into CNF form, making it suitable for SAT solvers. We present and investigate five BCT CNF encodings. We compare the propagation strength of the BCT CNF encodings and experimentally evaluate the encodings on a range of existing benchmarks. We also compare with seven existing CNF encodings of MDD constraints. Experimental results show that the CNF encodings of BCT constraints can outperform those of MDD constraints on various benchmarks.
Cite as
Ruiwei Wang and Roland H. C. Yap. CNF Encodings of Binary Constraint Trees. In 28th International Conference on Principles and Practice of Constraint Programming (CP 2022). Leibniz International Proceedings in Informatics (LIPIcs), Volume 235, pp. 40:1-40:19, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2022)
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@InProceedings{wang_et_al:LIPIcs.CP.2022.40,
author = {Wang, Ruiwei and Yap, Roland H. C.},
title = {{CNF Encodings of Binary Constraint Trees}},
booktitle = {28th International Conference on Principles and Practice of Constraint Programming (CP 2022)},
pages = {40:1--40:19},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-240-2},
ISSN = {1868-8969},
year = {2022},
volume = {235},
editor = {Solnon, Christine},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.CP.2022.40},
URN = {urn:nbn:de:0030-drops-166698},
doi = {10.4230/LIPIcs.CP.2022.40},
annote = {Keywords: BCT, CNF, MDD, NFA / MDD constraint, propagation strength}
}
Document
Modeling and Solving Parallel Machine Scheduling with Contamination Constraints in the Agricultural Industry
Abstract
Modern-day factories of the agricultural industry need to produce and distribute large amounts of compound feed to handle the daily demands of livestock farming. As a highly-automated production process is utilized to fulfill the large-scale requirements in this domain, finding efficient machine schedules is a challenging task which requires the consideration of complex constraints and the execution of optional cleaning jobs to prevent a contamination of the final products. Furthermore, it is critical to minimize job tardiness in the schedule, since the truck routes which are used to distribute the products to customers are sensitive to delays. Thus, there is a strong need for efficient automated methods which are able to produce optimized schedules in this domain.
This paper formally introduces a novel real-life problem from this area and investigates constraint-modeling techniques as well as a metaheuristic approach to efficiently solve practical scenarios. In particular, we investigate two innovative constraint programming model variants as well as a mixed integer quadratic programming formulation to model the contamination constraints which require an efficient utilization of variables with a continuous domain. To tackle large-scale instances, we additionally provide a local search approach based on simulated annealing that utilizes problem-specific neighborhood operators.
We provide a set of new real-life problem instances that we use in an extensive experimental evaluation of all proposed approaches. Computational results show that our models can be successfully used together with state-of-the-art constraint solvers to provide several optimal results as well as high-quality bounds for many real-life instances. Additionally, the proposed metaheuristic approach could reach many optimal results and delivers the best upper bounds on many of the large practical instances in our experiments.
Cite as
Felix Winter, Sebastian Meiswinkel, Nysret Musliu, and Daniel Walkiewicz. Modeling and Solving Parallel Machine Scheduling with Contamination Constraints in the Agricultural Industry. In 28th International Conference on Principles and Practice of Constraint Programming (CP 2022). Leibniz International Proceedings in Informatics (LIPIcs), Volume 235, pp. 41:1-41:18, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2022)
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@InProceedings{winter_et_al:LIPIcs.CP.2022.41,
author = {Winter, Felix and Meiswinkel, Sebastian and Musliu, Nysret and Walkiewicz, Daniel},
title = {{Modeling and Solving Parallel Machine Scheduling with Contamination Constraints in the Agricultural Industry}},
booktitle = {28th International Conference on Principles and Practice of Constraint Programming (CP 2022)},
pages = {41:1--41:18},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-240-2},
ISSN = {1868-8969},
year = {2022},
volume = {235},
editor = {Solnon, Christine},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.CP.2022.41},
URN = {urn:nbn:de:0030-drops-166701},
doi = {10.4230/LIPIcs.CP.2022.41},
annote = {Keywords: Parallel Machine Scheduling, Contamination Constraints, Constraint Programming, Mixed Integer Quadratic Progamming, Metaheuristics, Local Search, Simulated Annealing}
}