Please see the time has been updated to 11am Aadityan Ganesh will the General Exam "To Burn or Not to Burn: Hamlet Revisited for Simple Plain-Text Transaction Fee Mechanism Design" on 4/28/25 at 11am in CS 302. Committee: Matt Weinberg, Mark Braverman, Pramod Viswanath Abstract: Transaction fee mechanisms (TFMs) determine which subset of transactions are included in a block. Following Roughgarden (2020), we consider a “good” TFM to be one that is on-chain simple—that is, incentive compatible for both users and miners. We propose an additional criterion: off-chain influence proofness, meaning miners should not be able to improve their expected revenue by conducting separate, off-chain auctions. While cryptographic second-price auctions satisfy both properties, they rely on heavy cryptographic machinery. We investigate whether similarly robust guarantees can be achieved through mechanisms that are simple-to-participate in (i.e, are both on-chain simple and off-chain influence proof) and do not require cryptography. Our results are twofold. First, we establish a burn identity that precisely characterizes the portion of user payments that must be burned for a TFM to be off-chain influence proof. A TFM satisfies off-chain influence proofness if and only if its allocation rule X and burn rule B satisfy the payment identity in a multi-item single-buyer setting (Rochet, 1985) where the buyer's values for the n items correspond to the Myerson virtual values of the n users in the original TFM environment. Second, we build on the burn identity to characterize all deterministic plain-text TFMs that are simple-to-participate. These mechanisms are precisely posted-price mechanisms, where the price is set by the blockchain and each transaction has a specially tailored fixed burn. However, posted-price mechanisms require an infinite block capacity. Perhaps surprisingly, we also show the existence of simple-to-participate randomized TFMs that remain feasible even with finite block sizes. Holistically, our results show that while off-chain influence proofness is a fairly stringent requirement, families of on-chain simple and off-chain influence proof mechanisms can be found for a variety of settings.