proposition: Lemma variationsxx a f : variations a a f = [set 0].
proof: Proof. apply/seteqP; split => [x [_ /itv_partitionxx ->]|x ->]. by rewrite /variation big_nil => <-. by exists [::] => //=; rewrite /variation /= big_nil. 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)