fact: Definition zify_exprn e1 n := ZifyRing (rval e1 ^+ n) (zval e1 ^+ n) (zify_exprn_subproof e1 n).
imports: mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat choice seq) mathcomp(fintype finfun bigop order ssralg ssrnum ssrint)