Multiple Proposer Transaction Fee Mechanism Design ∞ Robust Incentives against Censorship and Bribery
Censorship resistance is one of the core value proposition of blockchains. A recurring design pattern aimed at providing censorship resistance is enabling multiple proposers to contribute inputs into block construction. Notably, Fork-Choice Enforced Inclusion Lists (FOCIL) is proposed to be included in Ethereum. However, the current proposal relies on altruistic behavior, without a Transaction Fee Mechanism (TFM). This study aims to address this gap by exploring how multiple proposers should be rewarded to incentivize censorship resistance. The main contribution of this work is the identification of TFMs that ensure censorship resistance under bribery attacks, while also satisfying the incentive compatibility properties of EIP-1559. We provide a concrete payment mechanism for FOCIL, along with generalizable contributions to the literature by analyzing 1) incentive compatibility of TFMs in the presence of a bribing adversary, 2) TFMs in protocols with multiple phases of transaction inclusion, and 3) TFMs of protocols in which parties are uncertain about the behavior and the possible bribe of others.
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Briefing
This paper addresses the critical problem of censorship vulnerability in blockchain networks, which arises from the current single-proposer model, and highlights the inadequacy of existing multi-proposer designs like Fork-Choice Enforced Inclusion Lists (FOCIL) due to their reliance on altruistic behavior. The foundational breakthrough lies in identifying and designing robust Transaction Fee Mechanisms (TFMs) that not only ensure censorship resistance against sophisticated bribery attacks but also uphold the incentive compatibility principles established by EIP-1559. This new theory proposes a concrete payment mechanism for FOCIL, thereby transforming the future of blockchain architecture by enabling economically sound, censorship-resistant block production.

Context
Before this research, a prevailing theoretical limitation in blockchain design was the susceptibility to censorship, largely due to the single-proposer model where one entity holds unilateral control over transaction inclusion and ordering within a block. While proposals like Fork-Choice Enforced Inclusion Lists (FOCIL) aimed to decentralize block production by enabling multiple proposers, these designs critically overlooked the economic incentives, assuming altruistic behavior. This theoretical gap left blockchains vulnerable to bribery attacks, where malicious actors could still influence transaction ordering or exclusion by compensating proposers, thereby undermining the core value proposition of censorship resistance.

Analysis
The paper’s core mechanism introduces specifically designed Transaction Fee Mechanisms (TFMs) to overcome the limitations of altruism in multi-proposer systems. The new primitive is a TFM framework that robustly incentivizes multiple block proposers to resist censorship and bribery. It fundamentally differs from previous approaches by integrating economic incentives directly into the multi-proposer architecture.
This involves analyzing how proposers should be rewarded to ensure that including transactions, even those targeted for censorship by a bribing adversary, remains economically rational. The logic extends EIP-1559’s incentive compatibility, adapting it to a multi-proposer environment where parties might be uncertain about the behavior and potential bribes of others, ensuring that the system remains secure and fair under adversarial conditions.

Parameters
- Core Concept ∞ Transaction Fee Mechanism Design
- New System/Protocol Focus ∞ Fork-Choice Enforced Inclusion Lists (FOCIL)
- Key Authors ∞ Yulin Ma, Zichen Fan, Qiang Wang
- Key Problem Addressed ∞ Censorship Resistance
- Incentive Standard ∞ EIP-1559 Compatibility

Outlook
This research opens new avenues for developing more resilient and decentralized blockchain architectures. The immediate next steps involve the formal integration and testing of these robust Transaction Fee Mechanisms within existing multi-proposer frameworks, particularly FOCIL. In the next 3-5 years, this theory could unlock real-world applications such as truly censorship-resistant transaction processing, fairer transaction ordering in decentralized exchanges, and enhanced security for critical on-chain operations. It also paves the way for further academic inquiry into incentive-compatible mechanism design under dynamic adversarial conditions and multi-agent uncertainty in distributed systems.