Talk:History of the separation axioms

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untitled[edit]

Yes, I am working on this. — Toby 02:41 Aug 9, 2002 (PDT)

Thanks, this looks like a good start. We might consider doing a table outlining the various common definition sets that are in use, such as Willard's and Steen and Seebach's. Then again, maybe it would get to cluttered to be useful. -- Fropuff 15:36, 2005 Feb 8 (UTC)

Reference to Wikipedia should be avoided (WP:SELF). Charles Matthews 09:25, 5 October 2007 (UTC)

Surely a merger with the Separation Axioms article is in order? —Preceding unsigned comment added by 41.241.91.225 (talk) 22:05, 28 November 2008 (UTC)

On the contrary, this was split out of Separation axiom to avoid confusing readers about the different definitions. (See this old version for what that could look like.) The problem is that it's not clear to me how much can even be written about this without original research, which is why I haven't been able to finish it. —Toby Bartels (talk) 20:50, 13 July 2009 (UTC)

One possibility would be to merge an abbreviated form of this into Separation axiom as a new section, towards the bottom, on terminological variations. Potentially, that could even include the table that Fropuff called for above, but it would not have a whole history. Until the history can be written without OR, that may be the best thing to do, although I'm not up to doing it myself yet. —Toby Bartels (talk) 19:31, 24 July 2009 (UTC)

So I just rated my own abandoned page, moderately. —Toby Bartels (talk) 06:23, 31 December 2011 (UTC)

Contradiction in terms[edit]

The last sentence in "Origins" reads

  For example, a regular space (called T3) does not have to be a Hausdorff space (called T2),
  at least not according to the simplest definition of regular spaces.

All the sources I can find state the T3 axiom as (T1 and regular), which is equivalent to regular Hausdorff. It may well be possible that there is an example of "Tj does not imply Ti, even though i<j", but this example is simply confusing. I think the example given of "T3 does not imply T2" should either be changed or removed completely. Espen180 (talk) 11:09, 15 February 2013 (UTC)

The reality is confusing, that's the point. For a reference in which T3 need not be T2, see Steen & Seebach (cited in the article). --Toby Bartels (talk) 21:31, 25 May 2013 (UTC)