proposition: Lemma imset_set0_subset {A B} (f : A -> B) (s : set B) : (f @: set0) \subset s.
proof: Proof. firstorder. Qed.
imports: mathcomp.ssreflect.ssreflect Classes.RelationClasses Classes.Morphisms List Tactics mathcomp(ssrfun ssrbool ssrnat seq)