src/ZF/Main_ZF.thy
2012-03-15 ago replacing ":" by "\<in>"
2012-03-06 ago mathematical symbols instead of ASCII
2011-11-24 ago modernized some old-style infix operations, which were left over from the time of ML proof scripts;
2010-04-29 ago proper context for mksimps etc. -- via simpset of the running Simplifier;
2009-01-21 ago dropped ID
2008-03-19 ago eliminated change_claset/simpset;
2008-02-11 ago Made theory names in ZF disjoint from HOL theory names to allow loading both developments