proposition: Lemma sizes1 (T : choiceType) (x : T) : size [fset x] = 1.
proof: Proof. by rewrite fset1Es. Qed.
imports: Relations Lia Setoid Morphisms mathcomp(all_ssreflect) CompDecModal.libs(edone bcase fset base modular_hilbert sltype rewrite_inequality fset_tac)