most recent 30 from http://mathoverflow.net 2013-05-21T17:39:39Z http://mathoverflow.net/feeds/user/14262 http://www.creativecommons.org/licenses/by-nc/2.5/rdf http://mathoverflow.net/questions/60457/elementaryshortuseful/61260#61260 Andy 2011-04-11T04:35:57Z 2011-04-11T04:35:57Z

<p>Sperner's Theorem on antichains in subset lattice and the Sunflower Lemma. Two great theorems in combo which require little to no theory to introduce and have extremely beautiful proofs. </p>