Furthermore, let <math>p_{X|Y=y}(x) = p_{(X,Y)}(x,y) / p_Y(y)</math> be the conditional mass or density function. Then, we have the identity | Furthermore, let <math>p_{X|Y=y}(x) = p_{(X,Y)}(x,y) / p_Y(y)</math> be the conditional mass or density function. Then, we have the identity |