Briefing
The modular blockchain paradigm introduces a critical centralization vector → the rollup sequencer, which controls transaction ordering and liveness, leading to censorship and Maximal Extractable Value (MEV) vulnerabilities. The Based Sequencing model resolves this by fundamentally decoupling the sequencing function from the rollup operator, assigning it directly to the Layer 1 (L1) proposer set. This foundational breakthrough re-architects the rollup stack, allowing L2 blocks to be permissionlessly included in the L1 block by the L1 proposer, effectively inheriting the L1’s liveness and credible neutrality. The most important implication is the elimination of the sequencer as a single point of failure, enabling shared sequencing across multiple rollups and unlocking synchronous composability.
Context
Prior to this research, rollups predominantly relied on a single, centralized sequencer or a small, permissioned set of sequencers. This architecture, while providing fast pre-confirmations and high throughput, introduced a significant trust assumption. The sequencer could censor transactions, halt the chain (liveness failure), or extract toxic MEV. The prevailing challenge was designing a decentralized sequencing mechanism that could match the performance of a centralized one without introducing a new, complex consensus layer or relying on vulnerable escape hatches, a design that would degrade settlement guarantees and risk mass exits.
Analysis
Based Sequencing operates by defining an L1-sequenced rollup whose transaction ordering is driven by the L1. The core mechanism leverages the existing Proposer-Builder Separation (PBS) on the L1. The L1 block builder is incentivized to include the next L2 block within their L1 bundle. The L1 proposer then includes this bundle in the L1 block.
This architecture ensures that the L2 block’s ordering is determined by the most decentralized and economically secure actor → the L1 proposer. The L1-sequenced rollup block is the new primitive, requiring no external sequencer signature verification or dedicated L2 consensus, drastically simplifying the architecture and inheriting L1 security guarantees.
Parameters
- L1 Proposer Set → The set of actors now responsible for sequencing, representing the most credibly neutral entity in the ecosystem.
- Zero Gas Overhead → The gas cost for sequencing is eliminated because no sequencer signature verification is required.
- L1 Slot Time → The base time unit for L2 block settlement, which determines the finality latency.
- Preconfirmations → Guarantees from the sequencer before an L2 block is published, mitigating the latency caused by long L1 slot times.
Outlook
The research opens a new avenue for rollup design, shifting the focus from building complex L2 consensus protocols to optimizing the L1-L2 communication layer. Future research will concentrate on refining the preconfirmation mechanism to mitigate the L1 slot time latency, ensuring an excellent user experience while maintaining L1 security. The strategic application of this theory is the development of a shared sequencing market, where multiple rollups can synchronously compose transactions, leading to a more unified, high-performance modular ecosystem within the next three to five years.
Verdict
The Based Sequencing model represents a critical theoretical inflection point, fundamentally solving the rollup centralization dilemma by cryptoeconomically aligning L2 transaction ordering with L1 security.
