fact: Record setoid : Type := mk_setoid {tset:>Type; Seq:tset->tset->Prop; Seq_refl : forall x :tset, Seq x x; Seq_sym : forall x y:tset, Seq x y -> Seq y x; Seq_trans : forall x y z:tset, Seq x y -> Seq y z -> Seq x z}.