def match_termsets(premises, facts, varmap):
    """
    prüft, ob sich für jede Prämisse ein Fakt passender Fakt findet
    """
    varnames = frozenset(varmap)
    for facts_mapping in itertools.product(facts, repeat=len(premises)):
        try:
            for i, premise in enumerate(premises):
                premise.match(facts_mapping[i], varmap)
            return
        except MatchException:
            map(varmap.__delitem__, frozenset(varmap) - varnames)
    raise MatchException('match failed')