proposition: Lemma dec_segment_image a b f : f b <= f a -> f @`[a, b] = `[f b, f a].
proof: Proof. by case: ltrP. Qed.
imports: HB(structures) mathcomp(all_ssreflect ssralg ssrint ssrnum finmap matrix) mathcomp(rat interval zmodp vector fieldext falgebra) mathcomp(mathcomp_extra boolp classical_sets functions) mathcomp(cardinality set_interval Rstruct) ereal reals signed topology prodnormedzmodule