proposition: Lemma inv_V {A x y} (p : x = y :> A) : eq_sym (eq_sym p) = p.
proof: Proof. case p; reflexivity. Defined.
imports: Coq.Lists.List Coq.Lists.SetoidList Coq.Bool.Bool Coq.Arith.PeanoNat Coq.Strings.Ascii Coq.Strings.String Coq.Logic.Eqdep_dec Fiat.Common