where <math>p_{(X,Y)}</math> is the joint probability mass function of <math>X</math> and <math>Y</math>, and <math>p_X</math> and <math>p_Y</math> are the marginal probability mass functions of <math>X</math> and <math>Y</math> respectively. | where <math>p_{(X,Y)}</math> is the joint probability mass function of <math>X</math> and <math>Y</math>, and <math>p_X</math> and <math>p_Y</math> are the marginal probability mass functions of <math>X</math> and <math>Y</math> respectively. |