proposition: Lemma contract_eq0 x : (contract x == 0%R) = (x == 0).
proof: Proof. by rewrite -(can_eq contractK) contract0. Qed.
imports: HB(structures) mathcomp(all_ssreflect all_algebra finmap) mathcomp(mathcomp_extra boolp classical_sets functions) mathcomp(fsbigop cardinality set_interval) reals signed topology constructive_ereal