The diagram above depicts a payoff matrix for a duopoly. If initially firms X and Y are charging $5 and $4 respectively: O both firms would find it advantageous to collude to raise their prices by $1 each 0 X will find it advantageous to raise its price if it was certain Y would not alter its price. 0 Y will find it advantageous to raise its price if it was certain X would not alter its price. 0 the two firms will be maximizing joint profits