Transaction fee mechanism design is a new decentralized mechanism design problem where users bid for space on the blockchain. Several recent works showed that the transaction fee mechanism design fundamentally departs from classical mechanism design. They then systematically explored the mathematical landscape of this new decentralized mechanism design problem in two settings: in the plain setting where no cryptography is employed, and in a cryptography-assisted setting where the rules of the mechanism are enforced by a multi-party computation protocol. Unfortunately, in both settings, prior works showed that if we want the mechanism to incentivize honest behavior for both users as well as miners (possibly colluding with users), then the miner revenue has to be zero. Although adopting a relaxed, approximate notion of incentive compatibility gets around this zero miner-revenue limitation, the scaling of the miner revenue is nonetheless poor. In this paper, we show that if we make a mildly stronger reasonable-world assumption than prior works, we can circumvent the known limitations on miner revenue, and design auctions that generate optimal miner revenue. We also systematically explore the mathematical landscape of transaction fee mechanism design under the new reasonable-world and demonstrate how such assumptions can alter the feasibility and infeasibility landscape.

翻译：交易费用机制设计是一个新的去中心化机制设计问题，用户竞标区块链上的存储空间。近期多项研究表明，交易费用机制设计从根本上区别于经典机制设计。这些研究随后系统性地探索了这一新型去中心化机制设计问题在两种场景中的数学图景：一是不使用密码学的普通场景，二是通过多方计算协议强制执行机制规则的密码辅助场景。遗憾的是，在两种场景中，先前研究表明，若要使机制激励用户和矿工（可能相互勾结）均保持诚实行为，则矿工收益必须为零。尽管采用宽松的近似激励相容概念可以绕过这一零矿工收益限制，但矿工收益的规模仍然不尽人意。本文证明，若做出比先前工作略强的合理世界假设，则可规避已知的矿工收益限制，并设计出能够实现最优矿工收益的拍卖机制。我们还系统性地探索了在新合理世界假设下交易费用机制设计的数学图景，并展示了这种假设如何改变可行性及不可行性的边界。