Actors and Blockchains, Together

This paper introduces FastSet, a novel distributed protocol that blends the parallelism of the actor model with the decentralization of blockchains to enable massively scalable, verifiable claim settlement without requiring global consensus. Unlike blockchains that enforce total ordering and strong consistency—leading to performance bottlenecks—FastSet allows claims (e.g., payments, asset transfers, identity attestations, or AI computations) to be independently validated and settled by validators without coordination, as long as they are weakly independent (i.e., they don’t conflict). Inspired by FastPay and CRDTs, FastSet clients (which can be users, apps, or agents) issue signed claims and optionally rely on verifiers to prove correctness, while validators replicate and settle global state independently. The paper includes a formal protocol design, correctness guarantees (security, determinism, liveness), and actor-inspired programming examples in a domain-specific language called setl, covering use cases like voting, digital asset transfers, and auctions. The result is a highly concurrent, verifiable infrastructure that could serve as the foundation for next-gen decentralized applications—not the next blockchain, but what the next 10,000 blockchains can build on.