fact: Definition prec (h: list Label)(l l': Label) := exists h1 h2 h3, h = h1 ++ (l :: h2) ++ (l' :: h3).
imports: Coq(FunctionalExtensionality Arith Lia) Coq(Arith.Peano_dec Arith.Compare_dec) Coq(Relations.Relation_Operators) Coq(List) Chapar(Predefs)