fact: Definition partdomsh n1 n2 (s1 s2 : seq nat) := all (fun i => n1 + sumn (take i s1) <= n2 + sumn (take i s2)) (iota 0 (size s1).+1).
imports: HB(structures) mathcomp(all_ssreflect) mathcomp(div ssralg ssrint ssrnum binomial) tools combclass sorted ordtype