src/HOL/Decision_Procs/ex/Commutative_Ring_Ex.thy
2015-06-20 wenzelm 2015-06-20 isabelle update_cartouches;
2014-11-02 wenzelm 2014-11-02 modernized header uniformly as section;
2012-09-03 wenzelm 2012-09-03 tuned proofs;
2012-07-24 wenzelm 2012-07-24 modernized imports;
2009-10-30 haftmann 2009-10-30 moved Commutative_Ring into session Decision_Procs