proposition: Lemma sub_inter : forall A B C, C ⊆ A -> C ⊆ B -> C ⊆ A ∩ B.
proof: Proof. intros A B C HA HB ? [? | ?]. now apply HA. now apply HB. Qed.
imports: RelationClasses Morphisms ClassicalRealizability.ShallowEmbedding ClassicalRealizability.Tactics ClassicalRealizability.BasicResults