fact: Definition exmatch (m : matching) (x : variable) (t : term) := match VM.find x m with | None => Some (VM.add x t m) | Some u => if t =T u then Some m else None end.
imports: Coq(Peano_dec Bool) CoLoR(LogicUtil EqUtil NatUtil VecUtil ATerm ASubstitution FSetUtil FMapUtil ListUtil)