def _rules_attr(cls):
        """Return the name of the attribute with rules for :meth:`create`"""
        from qnet.algebra.core.algebraic_properties import (
            match_replace, match_replace_binary)
        if match_replace in cls.simplifications:
            return '_rules'
        elif match_replace_binary in cls.simplifications:
            return '_binary_rules'
        else:
            raise TypeError(
                "class %s does not have match_replace or "
                "match_replace_binary in its simplifications" % cls.__name__)