Briefing
A foundational problem in decentralized finance is the extraction of Miner Extractable Value (MEV) from Automated Market Makers (AMMs) by block producers who exploit arbitrage opportunities through transaction reordering and censorship. This research proposes a new AMM mechanism that processes all transactions within a block as a single, governed batch, fundamentally decoupling the block producer’s sequencing control from their ability to profit. The core breakthrough is proving this application-layer mechanism achieves arbitrage resilience for single-proposer blockchains and the stronger guarantee of incentive compatibility when deployed on chains with sequencing fairness, signaling a path to mathematically provable strategy-proof DeFi primitives.
Context
The prevailing challenge in decentralized finance architecture is the centralization risk introduced by MEV. Block producers, possessing control over transaction inclusion and ordering, can front-run and back-run user trades on AMMs to capture risk-free arbitrage profit. This dynamic has fostered a centralized, off-chain ecosystem for transaction ordering, which deviates from the core decentralized equilibrium envisioned by blockchain designers. Prior academic work demonstrated the impossibility of fully resolving this application-level MEV through Transaction Fee Mechanism (TFM) design alone, necessitating a mechanism design solution at the smart contract layer itself.
Analysis
The paper introduces a new AMM swap mechanism that fundamentally shifts from sequential, intra-block transaction processing to a unified batch processing model. Instead of applying trades one by one, the mechanism aggregates all transactions within a block and executes them simultaneously according to pre-defined rules that ensure a constant potential function (e.g. the constant-product invariant) is maintained for the batch as a whole. This eliminates the block producer’s ability to gain from transaction ordering, as the final state change is independent of the sequence, thereby proving arbitrage resilience. The mechanism’s logic is designed to ensure that even if a block producer controls the block contents and sequencing, they cannot generate a risk-free profit, and users are treated fairly within the batch.
Parameters
- Arbitrage Resilience → Proven guarantee that a block producer cannot gain risk-free profit, even with full control over block contents and transaction sequencing.
- Incentive Compatibility → Stronger guarantee proven for blockchains that offer weak fair-sequencing, ensuring an individual user’s best strategy is to submit their true trade intention.
- Batch Processing → The core mechanism for transaction execution, where all orders in a block are processed as a single unit to eliminate intra-block sequencing profit.
- Constant Potential Function → The mathematical invariant (e.g. $x cdot y = k$) that the AMM pool must satisfy after the batch of transactions is processed.
Outlook
This theoretical work opens a crucial new avenue for decentralized application development, shifting the MEV mitigation burden from the consensus layer to the application layer. The immediate next step is the implementation and formal verification of this batch-processing primitive in production AMMs to validate its real-world performance and security guarantees. In the 3-5 year horizon, this concept could unlock a new generation of DeFi protocols where strategy-proofness is guaranteed by construction, leading to more equitable trading environments and potentially reducing the economic incentive for off-chain block production centralization. Future research will likely focus on extending these guarantees to compositional protocols and cross-block strategies.
Verdict
The introduction of an application-layer, batch-based mechanism design is a decisive step toward mathematically securing foundational DeFi primitives against the systemic centralization pressure of Miner Extractable Value.
