{ "schema_version": "1.2.0", "rubric_version": "1.1", "license": "CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/)", "record": { "id": "K-0011", "slug": "proof-of-useful-work", "title": "Proof of (useful) work", "aliases": [ "proof of work", "PoW", "proof of useful work", "PoUW" ], "status": "published", "last_reviewed": "2026-09-25", "review_interval_days": 90, "steward": null, "provenance": { "drafted_by": "ai", "reviewed_by": [ "codex-review" ] }, "risk_flags": [], "flags": [], "one_liner": "Evidence that a party spent a given amount of computation; in useful variants, the same work can also solve a problem someone wants solved.", "sources": [ { "source": "S-1607", "supports": "proofs of work proposed by Dwork and Naor: requester dedicates non-trivial computational work to each request; original uses against spam and denial of service; Bitcoin double spending", "locator": "abstract" }, { "source": "S-0005", "supports": "mining hashes message variants until one meets a target, which a verifier can check quickly", "locator": "'Proof-of-Work methods for crypto mining', in 'Verifying That Known Compute is Not Being Used for a Large Training Run'" }, { "source": "S-1608", "supports": "PoWs based on Orthogonal Vectors, 3SUM and All-Pairs Shortest Path whose work is useful; evaluation cannot be amortized across instances; energy waste motivation", "locator": "abstract" }, { "source": "S-1609", "supports": "PoUW for arbitrary matrix multiplication with 1+o(1) multiplicative overhead; GPUs could do AI work and mining at once", "locator": "abstract" }, { "source": "S-1105", "supports": "Pearl adapts the matrix-multiplication PoUW to FP8 on GPUs (provider-reported)", "locator": "abstract; ยง2" }, { "source": "S-0071", "supports": "independent measurement of Pearl's mainnet: random matrices pass verification", "locator": "abstract; measurement and verification sections" }, { "source": "S-1102", "supports": "proposal to use proof-of-work accounting to bound compute for unmonitored activity; needs a credible estimate of available compute; cannot discover an undeclared data centre (provider's own proposal)", "locator": "whole post" } ], "related": [ "K-0012", "K-0016" ], "type": "concept", "url": "https://trustbutveri.fyi/concepts/proof-of-useful-work/", "source_file": "content/concepts/proof-of-useful-work.md", "flags_all": [], "body_markdown": "A proof of work is evidence that a [[K-0001|prover]] spent a non-trivial amount of computation, which a verifier can check quickly; a proof of useful work lets that computation also solve a problem someone wants solved [[S-1607]] [[S-0005]] [[S-1608]].\n\nDwork and Naor proposed proofs of work to protect shared resources, for example against spam and denial of service, and Bitcoin later used them to prevent double spending [[S-1607]]. Conventional proofs of work waste the computation, so Ball and colleagues built ones whose work solves problems such as Orthogonal Vectors and 3SUM, and showed that the work cannot be amortized across instances [[S-1608]]. Komargodski and Weinstein give a proof of useful work for arbitrary matrix multiplication with 1 + o(1) multiplicative overhead, so that GPUs could do AI work and blockchain mining at once [[S-1609]]. [[I-0004|Pearl]]'s specification adapts the construction to FP8 matrix multiplication [[S-1105]]. The proof does not show where the matrices came from. On Pearl's network, an independent study found that random matrices passed verification [[S-0071]].\n\nAttestable proposes using proof-of-work accounting to bound the compute left for unmonitored activity, as in [[M-0007|proofs of useful work for capacity accounting]] [[S-1102]]. A proof shows that work was done, not that no other work was done: Attestable notes that its scheme needs a credible estimate of the compute available and cannot discover a data centre that was never declared [[S-1102]].", "body_text": "A proof of work is evidence that a prover spent a non-trivial amount of computation, which a verifier can check quickly; a proof of useful work lets that computation also solve a problem someone wants solved [S-1607] [S-0005] [S-1608]. Dwork and Naor proposed proofs of work to protect shared resources, for example against spam and denial of service, and Bitcoin later used them to prevent double spending [S-1607]. Conventional proofs of work waste the computation, so Ball and colleagues built ones whose work solves problems such as Orthogonal Vectors and 3SUM, and showed that the work cannot be amortized across instances [S-1608]. Komargodski and Weinstein give a proof of useful work for arbitrary matrix multiplication with 1 + o(1) multiplicative overhead, so that GPUs could do AI work and blockchain mining at once [S-1609]. Pearl's specification adapts the construction to FP8 matrix multiplication [S-1105]. The proof does not show where the matrices came from. On Pearl's network, an independent study found that random matrices passed verification [S-0071]. Attestable proposes using proof-of-work accounting to bound the compute left for unmonitored activity, as in proofs of useful work for capacity accounting [S-1102]. A proof shows that work was done, not that no other work was done: Attestable notes that its scheme needs a credible estimate of the compute available and cannot discover a data centre that was never declared [S-1102].", "referenced_by": [ { "id": "M-0007", "title": "Proofs of useful work for capacity accounting", "url": "https://trustbutveri.fyi/mechanisms/proofs-of-useful-work/" }, { "id": "M-0016", "title": "Timed challenge-response and memory-occupation challenges", "url": "https://trustbutveri.fyi/mechanisms/timed-challenge-response/" }, { "id": "I-0004", "title": "Pearl proof-of-useful-work blockchain", "url": "https://trustbutveri.fyi/implementations/pearl-proof-of-useful-work/" }, { "id": "K-0012", "title": "Proof of space", "url": "https://trustbutveri.fyi/concepts/proof-of-space/" } ] } }