} else if (ad->size() == domain().size()) {
} else if (ad == &domain()) {
  const StepDomain* exclude(const StepDomainChain*& sdc,			    const Name& name, size_t column) const {    const ActionDomain* ad = domain().exclude(name, column);    if (ad == NULL) {      return NULL;    } else if (ad->size() == domain().size()) {      return this;    } else {      sdc = new StepDomainChain(StepDomain(id(), parameters(), *ad), sdc);      return &sdc->head;    }  }