Talk:Group action

message: "In mathematics, an action of a group is a way of interpreting the elements of the group as "acting" on some space in a way that preserves the structure of that space."
Unfortunately, introducing a concept (group action) by using one of the words in the concept (action) — in quotes, yet ("acting") — is worse than unhelpful.  It is totally exasperating to anyone trying to understand the concept. It is the last thing we need in Wikipedia.2602:306:CF5D:1270:4023:7D48:4830:C217 (talk) 20:11, 27 August 2017 (UTC)
replies: text: I reworded the first sentence in the lead.  I think this is more clear.  In a mathematics article, describing a concept in simply understood terms, before the technical definition is made, is often difficult.—Anita5192 (talk) 21:54, 27 August 2017 (UTC)
thread_title:  Utterly unhelpful introductory sentence 

message: An editor recently changed all the center dot notations to baseline dots for the sake of uniformity in the article. I reverted, claiming that this was the wrong choice, with the intention of switching all the baseline dots to centered dots. Looking at the page I realized that this would be a mammoth job and the thought occurred to me that this might just be an English variant issue, and I should revert myself. All the references that I have checked either use a center dot or simple juxtaposition for the group action. I am not claiming any type of expertise here and am seriously asking where the baseline dot notation may be common? --Bill Cherowitzo  (talk) 16:39, 18 September 2017 (UTC)
replies: text: Apparently the baseline dot notation was introduced in 2012, see . I have never seen this notation outside of this article, but that doesn't mean much.  Tea2min (talk) 09:36, 19 September 2017 (UTC)

text: I've seen it used (and used it myself a long time ago) but I've always assumed that it was only out of laziness or not knowing the use of \cdot in latex. So it would not be out of place for this article to do so :) jraimbau (talk) 14:50, 19 September 2017 (UTC)
replies: text: I've converted to the center dots. I hope I've gotten them all. --Bill Cherowitzo  (talk) 04:56, 23 September 2017 (UTC)
replies: text: Thank you! 67.198.37.16 (talk) 07:01, 5 December 2023 (UTC)
thread_title:  Baseline dot notation 

message: There is a move discussion in progress on Talk:Permutation representation (disambiguation) which affects this page. Please participate on that page and not in this talk page section. Thank you.  —RMCD bot 20:31, 15 November 2017 (UTC)
thread_title:  Move discussion in progress 

message: The transitivity line of the section on types of group actions claims that the special linear group is transitive over a vector space. Surely this need not be true if the vector space has dimension 1 and the field is non-trivial. The special linear group of the real line is just multiplication by 1, which is not a transitive action on the reals.  — Preceding unsigned comment added by 140.194.194.252 (talk) 14:25, 22 June 2018 (UTC)
thread_title:  Transitivity of Special Linear Group 

message: I was wondering, if we can add the following definition to the second list in the Types of actions section:
*Covering space action if every point  x \in X  has a neighbourhood  U  such that \{g \in G : g \cdot U \cap U \neq \emptyset\} = e .
Since in the book Algebraic topology Allen Hatcher writes
"This is not standard terminology, but there does not seem to be a universally accepted name for [it]."
I assume this might be a matter of debate whether to list this as a standard definition. But since this book was (and still is) quite influential in the field of algebraic topology I'm asking if it justifies to just do it. K!r!93 (talk) 20:54, 22 April 2019 (UTC)
thread_title:  Covering Space Action 

message: I've read the paragraph about the orbit-stabiliser theorem many times now and I just can't understand it. The text is too condensed - it seems to try to introduce the theorem and prove it in a single sentence, and it does so in a way that doesn't build on what comes before it in the article. (This same sentence introduces the notion of coset for the first time, and also uses the word "translate" in a sense that's not familiar to me.)
It seems like this is a pretty important theorem, and the article would greatly benefit from spending a bit more time introducing the concepts behind the theorem and explaining what it shows. Nathaniel Virgo (talk) 19:32, 12 June 2019 (UTC)
replies: text: I added some explanation and a very simplistic example. If you are fine with it now, you can remove the tag.(I am not going to explain coset, there is a link to the corresponding page.)ChristianTS (talk) 15:52, 1 October 2019 (UTC)
thread_title:  Section on orbit-stabilizer theorem needs expanding