proposition: Lemma crs_restr (s : A -> Prop) r : (restr_rel s r)^⋈? ≡ ⦗fun _ => True⦘ ∪ restr_rel s r^⋈.
proof: Proof. rewrite !csE, !crsE. u. Qed.
imports: Program.Basics Arith micromega.Lia Permutation List Setoid HahnBase HahnList HahnRelationsBasic HahnSets