pPiPi1InparticularP2P1qpP1P0qpP1sinceP00sothatP3P2qpP2P1qp2P1andmoregenerallyPi1Piq piP10iNThusPi1P1iXk1Pk1PkiXk1q pkP1yieldingPi1P1P1iXk1q ID: 161321