2012-03-15 ago replacing ":" by "\<in>"
2012-03-14 ago rationalising the induction rule trans_induct3
2012-03-08 ago Structured and calculation-based proofs (with new trans rules!)
2012-03-06 ago Using mathematical notation for <-> and cardinal arithmetic
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
2007-10-07 ago modernized specifications;
2007-10-03 ago avoid unnamed infixes;
2005-06-17 ago migrated theory headers to new format
2004-06-02 ago new rules for simplifying quantifiers with Sigma
2003-05-28 ago some new ZF/UNITY material from Sidi Ehmety
2003-05-27 ago updating ZF-UNITY with Sidi's new material
2002-10-01 ago Numerous cosmetic changes, prompted by the new simplifier
2002-09-30 ago Adapted to new simplifier.
2002-07-14 ago improved presentation markup
2002-07-10 ago Fixed quantified variable name preservation for ball and bex (bounded quants)
2002-07-02 ago Tidying and introduction of various new theorems
2002-06-24 ago moving some results around
2002-06-19 ago conversion of Cardinal, CardinalArith
2002-05-28 ago deleted some useless ML bindings
2002-05-18 ago converted Arith, Univ, func to Isar format!
2002-05-13 ago converted Order.ML OrderType.ML OrderArith.ML to Isar format
2002-05-09 ago ordinal addition now coerces its arguments to ordinals
2001-11-09 ago eliminated old "symbols" syntax, use "xsymbols" instead;
2000-09-15 ago tuned symbols;
2000-08-24 ago added some xsymbols, and tidied
2000-08-18 ago X-symbols for ordinal, cardinal, integer arithmetic
1997-01-03 ago Implicit simpsets and clasets for FOL and ZF
1996-02-06 ago expanded tabs
1995-12-09 ago removed quotes from consts and syntax sections
1995-04-13 ago Defined ordinal difference, --
1995-01-12 ago Added constants Ord_alt, ++, **
1994-11-29 ago replaced "rules" by "defs"
1994-07-12 ago new cardinal arithmetic developments
1994-06-21 ago Addition of cardinals and order types, various tidying