Researchers from @Sei_Labs, the team behind @SeiNetwork ($SEI), and Solana developer @anza_xyz have published a paper comparing 39 designs in which several validators add transactions to the
Researchers from @Sei_Labs, the team behind @SeiNetwork ($SEI), and Solana developer @anza_xyz have published a paper comparing 39 designs in which several validators add transactions to the same block in parallel. The aim is to stop any single leader from deciding alone which transactions get in and in what order.
The paper, titled SoK: Multiple Concurrent Proposer Blockchains, is authored by Benjamin Marsh and Alejandro Ranchal-Pedrosa of Sei Labs and Max Resnick of Anza. Marsh is also affiliated with the University of Portsmouth.
According to the paper's abstract, multiple concurrent proposer (MCP) protocols let several parties contribute transactions to the same ledger update. The authors say they can spread communication and reduce one proposer's control over inclusion and order, but the benefits depend on how the contributions are combined.
The authors identify four direct MCP families: fixed proposal vectors, selected proposal collections, persistent proposal streams and causal proposal DAGs. They also compare these with what they call constrained assembly, where several parties restrict a block assembled by one party.
Across the 39 configurations, the study found that adding more proposers does not on its own guarantee that a given transaction is included. It also found that hiding transactions until a block is set does not stop someone from reacting last. The authors say these designs also need working recovery, payment and coordination rules to deliver reliable service.
The research touches both networks' product plans. Sei Labs describes Sei Giga as a multi-proposer EVM layer 1 architecture that uses the Autobahn consensus protocol. In a Sei blog post, the team says transactions have many paths to inclusion under multiple concurrent proposers, compared with a single-proposer system where a malicious proposer can temporarily censor them.
On the Solana side, Anza has published the Constellation whitepaper, a protocol design for multiple concurrent proposers on Solana. Four Pillars Research reported that, under the current spec, 16 proposers operate simultaneously.
Earlier academic work reached a similar cautious view. A 2023 paper on censorship resistance in on-chain auctions noted that multiple proposer protocols are not a panacea, pointing to unclear ordering, denial-of-service exposure and redundancy as open issues.
The new comparison suggests that the number of proposers is only one variable. How transactions are merged, recovered and paid for may matter as much for users hoping for fairer inclusion and ordering.
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