A minimal edge cover is an edge cover of a graph that is not a proper subset of any other edge cover.
Every minimum edge cover is a minimal edge cover, but the converse does not necessarily hold.
Minimal Edge Cover
See also
Edge Cover, Minimum Edge CoverExplore with Wolfram|Alpha
Cite this as:
Weisstein, Eric W. "Minimal Edge Cover." From MathWorld--A Wolfram Web Resource. https://mathworld.wolfram.com/MinimalEdgeCover.html