src/HOL/IMP/Abs_Int_init.thy
2013-08-13 kuncar 2013-08-13 remove unnecessary dependencies on Library/Quotient_*
2013-03-11 nipkow 2013-03-11 more factorisation of Step & Co
2013-03-10 nipkow 2013-03-10 factored out Step
2012-04-19 nipkow 2012-04-19 added revised version of Abs_Int