proposition: Lemma fst_if_eq {A B} : forall (dec : bool) (a : A) (b b' : B), fst (if dec then (a, b) else (a, b')) = a.
proof: Proof. destruct dec; eauto. Qed.
imports: Fiat.QueryStructure.Implementation.DataStructures.Bags.BagsInterface Fiat.QueryStructure.Implementation.DataStructures.Bags.BagsProperties Coq.Arith.PeanoNat Coq.FSets.FMapInterface Coq.FSets.FMapFacts Coq.FSets.FMapAVL Fiat.Common Fiat.Common.List.ListFacts Fiat.Common.List.FlattenList Fiat.Common.SetEqProperties Fiat.Common.FMapExtensions Fiat.Common.List.PermutationFacts