proposition: Lemma KeyFilter_true : forall k item, KeyFilter k item = true <-> E.eq (projection item) k.
proof: Proof. unfold KeyFilter; intros; destruct_if; intros; intuition. Qed.
imports: Fiat.QueryStructure.Implementation.DataStructures.Bags.BagsInterface Fiat.QueryStructure.Implementation.DataStructures.Bags.BagsProperties Coq.FSets.FMapInterface Coq.FSets.FMapFacts Coq.Arith.PeanoNat Fiat.Common Fiat.Common.List.ListFacts Fiat.Common.List.FlattenList Fiat.Common.SetEqProperties Fiat.Common.FMapExtensions Fiat.Common.List.PermutationFacts