proposition: Lemma restr_inter A (f : A -> Prop) r r' : restr_rel f (r ∩ r') ≡ restr_rel f r ∩ restr_rel f r'.
proof: Proof. u. Qed.
imports: Program.Basics Arith micromega.Lia Permutation List Setoid HahnBase HahnList HahnRelationsBasic HahnSets