User talk:Orthografer

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Hello Orthografer, and welcome to Wikipedia! Thank you for your contributions. I hope you like the place and decide to stay. Here are a few good links for newcomers:

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I replied on talk:Stein manifold. Cheers, Oleg Alexandrov (talk) 16:24, 13 December 2005 (UTC)[reply]

>> Hi, I noticed that you changed the symbols from ${\displaystyle \Gamma _{i\ell }^{m}}$ to ${\displaystyle \Gamma ^{m}{}_{i\ell }}$ in the above article. Recently another user changed it back and I've been asking why either edit happened. I'm very curious - can you explain your end? Orthografer 15:34, 21 August 2006 (UTC) <<[reply]

Even though the Christoffel symbol is not really a tensor, notationwise it behaves very much like one. For tensors, there is a notation in which each index is assigned its own "column", in which it is either a superscript or a subscript. In this notation (that I'm using), ${\displaystyle \Gamma ^{m}{}_{i\ell }}$ is explicitly different from ${\displaystyle \Gamma _{i}{}^{m}{}_{l}}$ or ${\displaystyle \Gamma _{il}{}^{m}}$, and if the m index is lowered, then the symbol becomes simply ${\displaystyle \Gamma _{mil}}$.

In the alternative notation, there are no "columns": the superscript is "independent" of the subscripts, and the indices might be arranged in a "Delta" (Δ) configuration, with the two subscripts forming the base and the superscript forming the top of the triangle (otherwise the superscript is flushed to the left, just like the subscripts). If the superscript (m) is lowered, the result is a Christoffel symbol of the first kind: ${\displaystyle \Gamma _{il,m}}$.

There is even a third notation, in which the Christoffel symbol of the second kind is ${\displaystyle \left\{{}_{i}{}^{m}{}_{l}\right\}}$, with the indices in a Delta configuration, and the Christoffel symbol of the first kind is ${\displaystyle [m,il]}$.

Which notation is used depends on the author. For example, Bernard F. Schutz (from Cambridge Uni) in his book A first course in general relativity uses the first notation (the one which I was using); Donald H. Menzel (from Harvard Uni) in his book Mathematical Physics uses the alternative notation; whereas Borisenko and Tarapov (from Russia) in their book Vector and Tensor Analysis with Applications use the third notation. Schutz always uses Christoffel symbols of the second kind, never of the first kind, and commas in the subscript row are reserved for differentiation (instead of for Christoffel symbols of the first kind) (see Covariant differentiation#Notation).

When I made the edits I happened to prefer the Cantabrigian notation, and now I notice that Wikipedia has kept it. The bracketed notation used by those two Russians I don't like: I definitely prefer the use of Gamma, whether it have its indices separated in columns or "independent" (whichever of these two alternatives is used, should not be a big deal, really). However, the Russian book is antiquated (copyrighted 1968) and checking the "Christoffel symbol" article in other languages (French, Spanish, German, Dutch, Russian, Chinese) one sees that they all use Gamma, though some use indices separated by columns (German, French, Russian) whereas some do not (Spanish, Dutch, Chinese). The Dutch version mentions the difference between Christoffel symbols of the first kind and of the second kind. The Spanish version ignores Christoffel symbols of the first kind, which so does the English, by the way (but so do the German, French, and Russian: just like Schutz). The Dutch version does not use a Gamma for the Christoffel symbol of the first kind: instead it uses brackets: ${\displaystyle [m,il]}$. Go figure... --AugPi 22:49, 11 November 2006 (UTC)[reply]

You just added a bit of a cryptic concern at Talk:Coriolis effect. The argument there has been dead since April. The article does not state that the Coriolis effect is important in tornadoes, only in cyclones, which agrees with Tornado#rotation. So where is the contradiction? Rracecarr 16:10, 19 August 2007 (UTC)[reply]

The second sentence in the cyclone article it says that "cyclone" is a general term that applies to tornadoes. Orthografer 23:15, 19 August 2007 (UTC)[reply]

Hi Orthografer—thanks for the barnstar, and glad you've enjoyed the edits! I studied manifolds and surgery for some time (and algebraic surfaces before that), and I've been writing up what I know; I've a few more general manifold contributions, and lots to write on surgery theory. Good luck with your research, and look forward to continuing to contribute! Nbarth (talk) 00:41, 17 November 2007 (UTC)[reply]

Hi there, I really don't understand how talk pages work around here, so it looked plausible that I'll have to notify you in person of some content I added to the talk page of Differential structure. Here it is, I hope you can help (& I promise to read up on how things are done in Wikipedia once I find the time...).

I also can't see this when I look at the article's talk page w/o having logged in - what a mess... Anyway, thanks! Athenray (talk) 11:21, 4 November 2008 (UTC)[reply]

Hi,
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Hi,
You appear to be eligible to vote in the current Arbitration Committee election. The Arbitration Committee is the panel of editors responsible for conducting the Wikipedia arbitration process. It has the authority to enact binding solutions for disputes between editors, primarily related to serious behavioural issues that the community has been unable to resolve. This includes the ability to impose site bans, topic bans, editing restrictions, and other measures needed to maintain our editing environment. The arbitration policy describes the Committee's roles and responsibilities in greater detail. If you wish to participate, you are welcome to review the candidates' statements and submit your choices on the voting page. For the Election committee, MediaWiki message delivery (talk) 13:33, 23 November 2015 (UTC)[reply]

Hello, Orthografer. Voting in the 2016 Arbitration Committee elections is open from Monday, 00:00, 21 November through Sunday, 23:59, 4 December to all unblocked users who have registered an account before Wednesday, 00:00, 28 October 2016 and have made at least 150 mainspace edits before Sunday, 00:00, 1 November 2016.

The Arbitration Committee is the panel of editors responsible for conducting the Wikipedia arbitration process. It has the authority to impose binding solutions to disputes between editors, primarily for serious conduct disputes the community has been unable to resolve. This includes the authority to impose site bans, topic bans, editing restrictions, and other measures needed to maintain our editing environment. The arbitration policy describes the Committee's roles and responsibilities in greater detail.

If you wish to participate in the 2016 election, please review the candidates' statements and submit your choices on the voting page. MediaWiki message delivery (talk) 22:08, 21 November 2016 (UTC)[reply]

Hello, Orthografer. Voting in the 2017 Arbitration Committee elections is now open until 23.59 on Sunday, 10 December. All users who registered an account before Saturday, 28 October 2017, made at least 150 mainspace edits before Wednesday, 1 November 2017 and are not currently blocked are eligible to vote. Users with alternate accounts may only vote once.

The Arbitration Committee is the panel of editors responsible for conducting the Wikipedia arbitration process. It has the authority to impose binding solutions to disputes between editors, primarily for serious conduct disputes the community has been unable to resolve. This includes the authority to impose site bans, topic bans, editing restrictions, and other measures needed to maintain our editing environment. The arbitration policy describes the Committee's roles and responsibilities in greater detail.

If you wish to participate in the 2017 election, please review the candidates and submit your choices on the voting page. MediaWiki message delivery (talk) 18:42, 3 December 2017 (UTC)[reply]

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