more symmetric
added lemmas; uniform names --HG-- rename : src/HOL/Data_Structures/Priority_Queue.thy => src/HOL/Data_Structures/Priority_Queue_Specs.thy
tuned order of arguments
dont rename PQ.del_min
del_min -> split_min
isabelle update_cartouches -c;
added PQ with merge
tuning
tuned
reorg
added Min_mset and Max_mset
separate file for priority queue interface; extended Leftist_Heap.
tuned proof
renaming
added is_empty
proper priority queue spec
added Leftist_Heap