We initiate the study of transaction fee mechanism design for blockchain protocols in which multiple block producers contribute to the production of each block. Our contributions include:- We propose an extensive-form (multi-stage) game model to reason about the game theory of multi-proposer transaction fee mechanisms.- We define the strongly BPIC property to capture the idea that all block producers should be motivated to behave as intended: for every user bid profile, following the intended allocation rule is a Nash equilibrium for block producers that Pareto dominates all other Nash equilibria.- We propose the first-price auction with equal sharing (FPA-EQ) mechanism as an attractive solution to the multi-proposer transaction fee mechanism design problem. We prove that the mechanism is strongly BPIC and guarantees at least a 63.2% fraction of the maximum-possible expected welfare at equilibrium.- We prove that the compromises made by the FPA-EQ mechanism are qualitatively necessary: no strongly BPIC mechanism with non-trivial welfare guarantees can be DSIC, and no strongly BPIC mechanism can guarantee optimal welfare at equilibrium.
View on arXiv@article{garimidi2025_2505.17885,
title={ Transaction Fee Mechanism Design for Leaderless Blockchain Protocols },
author={ Pranav Garimidi and Lioba Heimbach and Tim Roughgarden },
journal={arXiv preprint arXiv:2505.17885},
year={ 2025 }
}