fact: Definition widen_itv x i' (uni : unify_itv i' i) := Itv.mk (widen_itv_subproof x uni).
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool) mathcomp(ssrnat eqtype choice order ssralg ssrnum ssrint) mathcomp(interval) mathcomp(mathcomp_extra boolp) signed