src/HOL/Library/Perm.thy
13 months ago nipkow 2018-06-07 utilize 'flip'
18 months ago nipkow 2018-01-10 ran isabelle update_op on all sources
2017-01-17 wenzelm 2017-01-17 isabelle update_cartouches -c -t;
2016-10-02 wenzelm 2016-10-02 eliminated hard tabs;
2016-07-22 wenzelm 2016-07-22 tuned proofs -- avoid unstructured calculation;
2016-07-22 wenzelm 2016-07-22 tuned proofs -- avoid improper use of "this";
2016-07-11 wenzelm 2016-07-11 tuned;
2016-07-04 haftmann 2016-07-04 basic facts about almost everywhere fix bijections