proposition: Lemma absorbs_left_tc A (R S : rel A) : R @ S << S -> R! @ S << S.
proof: Proof. intro. unfold incl, compose. intros. do 2 destruct H0. gen H1. clear H1. elim H0; intros; auto. apply H. exists y0. auto. Qed.
imports: Coq(Setoid Basics Morphisms List Lia) CoLoR(LogicUtil)