most recent 30 from http://mathoverflow.net 2013-05-19T03:44:54Z http://mathoverflow.net/feeds/question/35893 http://www.creativecommons.org/licenses/by-nc/2.5/rdf http://mathoverflow.net/questions/35893/what-signs-are-there-that-a-problem-is-solvable unknown (yahoo) 2010-08-17T17:49:13Z 2010-08-17T17:49:13Z

<p>What signs are there that a problem is solvable, but not so easy that it isn't worthwhile doing, and not so hard like P=NP? </p>