Entropy submodularity for three independent sums (source code)

= Entropy submodularity for three independent sums

For independent finitely supported random variables $X,Y,Z$ in a <finite additive group>,
$$
H(X+Y+Z)+H(Y)\leq H(X+Y)+H(Y+Z).
$$
This is the <data processing inequality for mutual information> applied to the <Markov chain> $X\to X+Y\to X+Y+Z$.