proposition: Lemma seq_eqv_minus_lr A (s : A -> Prop) (r r' : relation A) : (r ⨾ ⦗s⦘) \ r' ≡ (r \ r') ⨾ ⦗s⦘.
proof: Proof. autounfold with unfolderDb; intuition; desf; eauto. Qed.
imports: Program.Basics Arith micromega.Lia Permutation List Setoid HahnBase HahnList HahnRelationsBasic HahnSets