Talk:PDIFF

Context

Added header. —Nils von Barth (nbarth) (talk) 22:44, 5 May 2009 (UTC)[reply]

This article needs more context. A short introduction what the topic is about can help. I came here in search for a software called pdiff. Does this explain some math used in pdiff, or is this unrelated?

77.24.237.81 (talk) 22:38, 7 June 2008 (UTC)[reply]

Sorry for the lack of context – I’ve substantially expanded this, which should provide better context.

AFAICT there is no relation whatsoever between the category PDIFF and any computer program by that name; this is a very technical point in math, and of likely very little interest outside it.

As for other uses of the term, I’ve create a disambiguation page at pdiff; hope this helps!

—Nils von Barth (nbarth) (talk) 22:44, 5 May 2009 (UTC)[reply]

Blank and restart

This article is completely wrong. PDiff does not form a category and thus almost every else stated is false. Just read the first page of the first reference by Jacob Lurie! Or [this MO answer by Tom Goodwillie](https://mathoverflow.net/a/27673). The only reputable source that says otherwise is McMullen, but he, in turn, cites Thurston, who is the very clearest against him. I can't link Thurston, but I quote exercise 3.10.1(a):

"Show that such maps [pdiff] don’t form a group. Thus, piecewise smooth maps serve as bridges between piecewise linear and smooth structures; they don’t work well alone."

A stub consisting of just the bibliography (ex McMullen) would be an improvement on this article. 108.52.140.137 (talk) 16:12, 29 June 2019 (UTC)[reply]