Changes

Changes from Mercurial (hg http://isabelle.in.tum.de/repos/isabelle/ default)

Changeset 71723:5bbd80875e02 by nipkow: merged
Changeset 71722:1cffe8f4d7b3 by nipkow: more automation and clarification
The file was modified	`src/HOL/Data_Structures/AVL_Set.thy`