Prior-free Collusion-proof Dynamic Mechanisms

For a general class of dynamic stochastic multi-player problems, Csóka, Liu, Rodivilov, and Teytelboym (2024) proposed prior-dependent mechanisms. The Guaranteed Utility Mechanism with transfers (TU-GUM) implements efficiency in a Guaranteed Utility Equilibrium (GUE). Its transfer-free variant (NTU-GUM) implements approximate efficiency in {\epsilon}-GUE. In this paper, we define prior-free versions of both TU-GUM and NTU-GUM. As a special case, we believe that the new prior-free NTU-GUM implements a 1.283-approximation to Pareto efficiency for the repeated single good allocation problem in Fikioris, Banerjee, and Tardos (2024).