/* update the dvg */
update_dvg(rss, &dvg, ser->v, ser->u);
update_dvg(rss, &dvg, get_rss_irn(rss, ser->edge->src), get_rss_irn(rss, ser->edge->tgt));
/* update the dvg */
update_dvg(rss, &dvg, ser->v, ser->u);
update_dvg(rss, &dvg, get_rss_irn(rss, ser->edge->src), get_rss_irn(rss, ser->edge->tgt));