Why should the first verifiers be sealed?
research/verifier-cascades
Sequential verifiers who see earlier verdicts herd: wrong-cascade probability exactly (1−a)²/(a²+(1−a)²), cascade after 2/(a²+(1−a)²) signals, accuracy capped at 0.845 (a=0.7) versus ≈1 for an independent majority, and a sealed first batch of ≥3 lifts the cap (0.875 at m=3, 0.949 at m=11); checked against Bayesian agents.
What it found
Verifiers who are paid for being right and see earlier verdicts herd: once two more revealed signals point one way than the other, everyone copies. With signal accuracy a the cascade is wrong with probability exactly (1−a)²/(a²+(1−a)²) (0.155 at a=0.7) and forms after 2/(a²+(1−a)²) revealed signals (3.4), so accuracy is capped at 0.845 however many verifiers join, versus ≈1 for an independent majority of 101. A sealed first batch of m ≥ 3 lifts the cap (0.875 at m=3, 0.949 at 11) and beats a majority of the same paid size. Recursion checked against fully Bayesian simulated agents. Stylised, symmetric signals.
A figure from its own output
Paper, code and results
More in Effort & peer prediction
- When should a paid verifier stop checking?Verifiers who choose when to stop checking under a proper score: optimal policy is a symmetric threshold (matches dynamic programming), closed-form accuracy
1/(1+((1−a)/a)^k)and costk(2p_k−1)/(2a−1), participationκ ≥ 4c/(2a−1)², and adaptive stopping matches fixed-sample accuracy with 2–3× fewer checks. - Peer-prediction markets for decentralized ML training verificationPeer-prediction and prediction-market mechanisms for verifying decentralized ML training, with adversarial evaluation.
- What does it cost to pay a verifier to check?Paying verifiers for costly checking effort with proper scoring rules: implementable efforts = concave envelope of the value curve, exact Brier rent
(n−1)/(a+b), log score needs half Brier's payout spread on rare-fault priors. - What does a proper score buy when effort is private?Scoring rules as limited-liability effort contracts: shirking threshold
2c/(kκ²), first best needs a fee, otherwise the principal keeps 48–68% of surplus. - How do you pay for effort when nobody knows the truth?Peer prediction without ground truth: output agreement pays 1.0 for laziness vs 0.68 for honesty, Dasgupta–Ghosh payoff
2p(1-p)g_i g_jexact, effort as a coordination game with thresholdc/(2p(1-p)κ²), and closed-form gold-check rate√(c·g_H/G). - Does agreement pay reward shared laziness?Peer prediction when lazy verifiers share a default answer: agreement pay is
2G·Cov, effort is a coordination game with thresholda*=(k/2G+s)/(pq+s), the all-lazy equilibrium always exists and pays as much as honesty when the default matches the prior, and gold checks needing more mass than the honest pay close it.
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Produced with AI assistance (Claude). Results are from the code in this repository and are simulated or stylised unless the abstract says otherwise; nothing here implies affiliation with or endorsement by any lab, researcher or company cited. MIT licensed.