fact: Definition add_nonzero_subdef (xnz ynz : nullity) (xr yr : reality) := nz_of_bool (add_samesign_subdef xnz ynz xr yr && (xnz || ynz)).
imports: HB(structures) Coq(ssreflect ssrfun ssrbool) mathcomp(ssrnat eqtype choice order ssralg ssrnum ssrint) mathcomp(mathcomp_extra)