Communication Complexity of Cake Cutting

We study classic cake-cutting problems, but in discrete models rather than using infiniteprecision real values, specifically, focusing on their communication complexity. Using general discrete simulations of classical infinite-precision protocols (Robertson-Webb and movingknife), we roughly partition the various fair-allocation problems into 3 classes: “easy” (constant number of rounds of logarithmic many bits), “medium” (poly-logarithmic total communication), and “hard”. Our main technical result concerns two of the “medium” problems (perfect allocation for 2 players and equitable allocation for any number of players) which we prove are not in the “easy” class. Our main open problem is to separate the “hard” from the “medium” classes.