I. DIFFERENTIAL ENTROPY AND THE GAUSSIAN CHANNEL A. Differential Entropy Let X be a random variable with a continuous alphabet. • FX(x) = Pr(X ≤ x) Cumulative Distribution Function {CDF}. F (x) is a short notation for FX(x). • fX(x) = dFX(x) dx Probability Density Function {PDF} (in this course we will assume that the derivative exists). f(x) is a short notation for fX(x). Definition 1 ( Differ...