src/Doc/Logics_ZF/ZF_examples.thy
2017-04-09 wenzelm 2017-04-09 clarified main ZF.thy / ZFC.thy, and avoid name clash with global HOL/Main.thy;
2014-11-02 wenzelm 2014-11-02 modernized header uniformly as section;
2014-11-01 wenzelm 2014-11-01 eliminated spurious semicolons;
2014-04-08 haftmann 2014-04-08 even more standardized doc session names after #b266e7a86485