for (size_t j=0; j<this->nops(); j++) {
if (!subsed[j] && tryfactsubs(op(j), it->first, nummatches, repls)) {
subsed[j] = true;
for (size_t j=0; j<this->nops(); j++) {
if (!subsed[j] && tryfactsubs(op(j), it->first, nummatches, repls)) {
subsed[j] = true;