proposition: Lemma variations_neq0 a b f : a < b -> variations a b f !=set0.
proof: Proof. move=> ab; exists (variation a b f [:: b]); exists [:: b] => //. exact: itv_partition1. Qed.
imports: mathcomp(all_ssreflect ssralg ssrint ssrnum finmap) mathcomp(matrix interval zmodp vector fieldext falgebra) mathcomp(mathcomp_extra boolp classical_sets functions) mathcomp(cardinality) ereal reals signed topology prodnormedzmodule normedtype derive sequences real_interval HB(structures)