Entropic vector (original) (raw)

The entropic vector or entropic function is a concept arising in information theory. It represents the possible values of Shannon's information entropy that subsets of one set of random variables may take. Understanding which vectors are entropic is a way to represent all possible inequalities between entropies of various subsets. For example, for any two random variables , their joint entropy (the entropy of the random variable representing the pair ) is at most the sum of the entropies of and of :