public function getAlternatingSequence()
    {
        $edges    = $this->edges->getVector();
        $vertices = $this->vertices->getVector();

        $ret = array();
        for ($i = 0, $l = count($this->edges); $i < $l; ++$i) {
            $ret []= $vertices[$i];
            $ret []= $edges[$i];
        }
        $ret[] = $vertices[$i];

        return $ret;
    }