fact: Definition slist_good n m E := [/\ slistp E, slength E = csucc(cmax n m) & forall i, i <c slength E -> (Vg E i) = \1c \/ (Vg E i) = \3c ].
imports: mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat) mathcomp(seq)