2012-03-21 ago More structured proofs for infinite cardinalities
2012-03-06 ago mathematical symbols instead of ASCII
2009-10-17 ago eliminated hard tabulators, guessing at each author's individual tab-width;
2008-02-11 ago Made theory names in ZF disjoint from HOL theory names to allow loading both developments
2005-06-17 ago migrated theory headers to new format
2002-10-01 ago Numerous cosmetic changes, prompted by the new simplifier
2002-07-14 ago improved presentation markup
2002-07-02 ago Tidying and introduction of various new theorems
2002-05-10 ago converted the AC branch to Isar
1994-08-12 ago installation of new inductive/datatype sections
1994-07-27 ago Addition of infinite branching datatypes