def parse_relation(fields):
    """
    Assumes all relation are binary, argument names are discarded
    :param fields: correspond to one Brat line seperated by tab
    :return: relation id, relation name, arg1 and arg2
    """
    rel, a1, a2 = fields[1].split(" ")
    rel_id = fields[0]
    return rel_id, rel, a1.split(":")[1], a2.split(":")[1]