Prior-free Collusion-proof Dynamic Mechanisms
Endre Csóka
TL;DR
The paper generalizes prior collusion-resistant dynamic mechanisms by introducing prior-free versions of the Guaranteed Utility Mechanism, applicable to both transferable and non-transferable utility settings. It develops a formal dynamic model with revelation and timing, defines universal feasibility and guaranteed utilities, and shows how to implement target welfare guarantees without fixed priors, using transfers or transfer-free schemes. A key result is a 1.283-approximation to Pareto efficiency in a repeated single-good allocation and a sequential good allocation construction that attains universal feasibility in TU, with NTU extensions and related robustness properties. The work advances robust mechanism design for dynamic multi-player environments and provides a framework for analyzing efficiency-robustness trade-offs under relaxed priors, with open questions about tightening bounds and extending to broader settings.
Abstract
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 ε-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).
