fact: Definition Prod (E:gset A) (F:gset B) : gset (A*B) := fun x => let (a,b) := x in E a /\ F b.
imports: Coq(RelationClasses Setoid Morphisms SetoidList Mergesort Permutation) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq fintype) mathcomp(bigop path) RegexpBrzozowski(glue)