Record Setoid : Type := 
  {Carrier :> Type; Equal : relation Carrier; Prf_equiv :> equivalence Equal}.Record Setoid : Type := 
  {Carrier :> Type; Equal : relation Carrier; Prf_equiv :> equivalence Equal}.Record Setoid : Type := 
  {Carrier :> Type; Equal : relation Carrier; Prf_equiv :> equivalence Equal}.Record Setoid : Type := 
  {Carrier :> Type; Equal : relation Carrier; Prf_equiv :> equivalence Equal}.

Lemma Sym : forall (E : Setoid) (x y : E), Equal x y -> Equal y x.