UAT20: Unifying Liquidity Across Rollups
Yue Li, Han Liu
TL;DR
The paper tackles liquidity fragmentation in Ethereum's multi-rollup ecosystem by introducing UAT20, a CRDT-based universal abstract token standard that unifies a user's ERC20 holdings across rollups. It defines a dual-token architecture with ERC20 $\Sigma_{20}$ and the globally synchronized UAT20 token $\Upsilon_{20}$, coordinated by a Synchronizer that interfaces with Ethereum $\mathcal{E}$ to order and commit cross-rollup transactions. A two-phase Execute-Commit protocol (Phase1: execution; Phase2: commit) plus an arbitration order resolves conflicts and ensures eventual consistency across $\mathcal{R}_i$, with $\mathbb{B}$ capturing global balances and per-rollup balances $\mathcal{B}^i_e$. Empirical analysis of 11 tokens across three rollups shows substantial cross-rollup token usage and liquidity aggregation activity, motivating the need for unification to reduce cross-rollup friction and improve DeFi efficiency. Overall, UAT20 aims to streamline liquidity access, reduce cross-chain risk, and strengthen Ethereum's multi-rollup ecosystem through a formally defined CRDT-driven framework plus a robust commit protocol.
Abstract
Ethereum has been a cornerstone of the decentralized ecosystem, with rollup-based scaling solutions like Arbitrum and Optimism significantly expanding its capabilities. These rollups enhance scalability and foster innovation, but their rapid proliferation has introduced \emph{liquidity fragmentation}. Specifically, tokens distributed on multiple rollups fragment the liquidity of users, complicating participation in trading and lending activities bound by minimum liquidity thresholds. This paper proposes UAT20, a universal abstract token standard, to address liquidity fragmentation across rollups. Leveraging Conflict-free Replicated Data Types (CRDTs), UAT20 ensures consistent states across multiple rollups. We introduce a two-phase commit protocol to resolve transaction conflicts, enabling seamless and secure liquidity unification. Finally, our empirical analysis demonstrated the necessity and effectiveness of UAT20 in mitigating liquidity fragmentation within Rollups.