Ahlswede–Daykin inequality

The Ahlswede–Daykin inequality is a result in information theory that relates to the concept of entropy and the joint distribution of random variables. It provides a connection between the joint entropy of a set of variables and the individual entropies of those variables, specifically in the context of entropy in multiple dimensions. To give a brief overview, let \( X \) and \( Y \) be two discrete random variables with joint distribution.