most recent 30 from http://mathoverflow.net 2013-05-19T07:45:57Z http://mathoverflow.net/feeds/user/30107 http://www.creativecommons.org/licenses/by-nc/2.5/rdf http://mathoverflow.net/questions/116837/collection-from-replacement-in-zfc-extensionality Frode Bjørdal 2012-12-20T02:40:05Z 2012-12-20T13:59:14Z

<p>My question is whether the axiom of extensionality is required to show that the schema of collection follows from the schema of replacement in the usual Zermelo-Fraenkel environment with choice. In other words: Is the schema of collection a theorem schema in Zermelo-Fraenkel set theory with choice minus the axiom schema of extensionality?</p>