User petrus - MathOverflowmost recent 30 from http://mathoverflow.net2013-05-24T01:04:00Zhttp://mathoverflow.net/feeds/user/11860http://www.creativecommons.org/licenses/by-nc/2.5/rdfhttp://mathoverflow.net/questions/1890/describe-a-topic-in-one-sentence/65532#65532Answer by Petrus for Describe a topic in one sentence.Petrus2011-05-20T12:07:50Z2011-05-20T14:50:45Z<p>I think this belongs on this list too:</p>
<p>The <em>theory of groups</em> is a branch of mathematics in which one does something to something and then compares the results with the result of doing the same thing to something else, or something else to the same thing. – <a href="http://www.mathacademy.com/pr/quotes/index.asp?ACTION=TOP&VAL=group%20theory" rel="nofollow">James Newman</a></p>
http://mathoverflow.net/questions/64905/which-book-would-you-like-to-see-texified/64910#64910Answer by Petrus for Which book would you like to see "texified"?Petrus2011-05-13T17:48:23Z2011-05-13T17:48:23Z<p>"Lectures on Chevalley Groups" - by Robert Steinberg</p>
http://mathoverflow.net/questions/1890/describe-a-topic-in-one-sentence/65532#65532Comment by PetrusPetrus2011-05-20T14:48:38Z2011-05-20T14:48:38Z@Todd Trimble If you study groups by their actions on sets, "$x^g$" is "doing g to x". Natural questions are like "when does $x^g = x^h$?" i.e. when does doing something different on the same thing give the same result? http://mathoverflow.net/questions/64905/which-book-would-you-like-to-see-texified/64910#64910Comment by PetrusPetrus2011-05-16T08:10:23Z2011-05-16T08:10:23Z@Emmanuel Kowalski: I would appreciate that as well, I've been looking forever by now.