2011-05-14 ago modernized functor names;
2011-04-20 ago eliminated Display.string_of_thm_without_context;
2010-07-08 ago tuned titles
2010-03-13 ago removed old CVS Ids;
2009-07-21 ago proper context for Display.pretty_thm etc. or old-style versions Display.pretty_thm_global, Display.pretty_thm_without_context etc.;
2008-05-17 ago structure Display: less pervasive operations;
2005-09-20 ago slight adaptions to library changes
2005-03-03 ago Move towards standard functions.
1998-02-25 ago renamed rep_claset to rep_cs
1997-12-19 ago adapted to new sort function;
1996-01-29 ago expanded tabs
1994-07-12 ago chain_tac: deleted; just use etac mp
1993-09-16 ago Initial revision