Users bid in a transaction fee mechanism (TFM) to get their transactions included and confirmed by a blockchain protocol. Roughgarden (EC'21) initiated the formal treatment of TFMs and proposed three requirements: user incentive compatibility (UIC), miner incentive compatibility (MIC), and a form of collusion-resilience called OCA-proofness. Ethereum's EIP-1559 mechanism satisfies all three properties simultaneously when there is no contention between transactions, but loses the UIC property when there are too many eligible transactions to fit in a single block. Chung and Shi (SODA'23) considered an alternative notion of collusion-resilience, called c-side-constract-proofness (c-SCP), and showed that, when there is contention between transactions, no TFM can satisfy UIC, MIC, and c-SCP for any c at least 1. OCA-proofness asserts that the users and a miner should not be able to "steal from the protocol" and is intuitively weaker than the c-SCP condition, which stipulates that a coalition of a miner and a subset of users should not be able to profit through strategic deviations (whether at the expense of the protocol or of the users outside the coalition). Our main result is the first proof that, when there is contention between transactions, no (possibly randomized) direct-revelation TFM satisfies UIC, MIC, and OCA-proofness. This result resolves the main open question in Roughgarden(EC'21). We also suggest several relaxations of the basic model that allow our impossibility result to be circumvented.

翻译：用户通过在交易费用机制（TFM）中出价，使其交易被区块链协议纳入并确认。Roughgarden（EC'21）首次对TFM进行形式化处理，提出了三个要求：用户激励兼容性（UIC）、矿工激励兼容性（MIC）以及一种称为OCA-proofness的共谋抵抗性。当交易之间无竞争时，以太坊的EIP-1559机制同时满足这三条性质，但当候选交易过多无法纳入单个区块时，则会丧失UIC性质。Chung和Shi（SODA'23）考虑了另一种共谋抵抗性概念，即c侧合同证明性（c-SCP），并证明当交易存在竞争时，对于任何c≥1，不存在满足UIC、MIC和c-SCP的TFM。OCA-proofness声明用户与矿工不应能"窃取协议收益"，直观上弱于c-SCP条件（后者规定矿工与某子集用户组成的联盟不应能通过策略性偏离获利，无论该获利是否以牺牲协议或联盟外用户为代价）。我们的主要结果是首次证明：当交易存在竞争时，不存在（可能随机化的）直接揭示型TFM同时满足UIC、MIC和OCA-proofness。该结果解决了Roughgarden（EC'21）中提出的主要开放问题。我们还提出了基本模型的若干松弛方案，以规避该不可能性结果。