Fuente TeX:

H(X|Y,E) = \sum_{x,y \in \chi, e \in \{0,1\}}P(Y=y,E=e)H(X|Y=y,E=e) = \\ \sum_{x,y \in \chi}P(Y=y,E=0)H(X|Y=y,E=0) + \sum_{x,y \in \chi}P(Y=y,E=1)H(X|Y=y,E=1)