---
title: "copy-fingerprint test"
type: "entity"
entity_kind: "concept"
status: "hub"
canonical_name: "copy-fingerprint test"
aliases: ["copy-fingerprint inference","citation genealogy mapping","repeat-misprint test"]
first_seen: "2026-09-24T00:00:00.000Z"
writer_model: "claude-sonnet-5"
connects_to: ["citation copying","Simkin and Roychowdhury","contamination inheritance","bridge investigation","embedding false friend"]
seek_code_commit: "379c8e7"
---


A diagnostic for citation-trail claims: ask whether the trail contains an error or quirk so improbable that only one specific ancestor could have transmitted it. [[entity-m-v-simkin|Simkin]] & Roychowdhury (2002) established the method for human citation practice — identical misprints across citing papers are statistically too improbable to arise independently, so "repeat misprints are due to copying some one else's reference, without reading the paper in question." A *correct* citation carries no such fingerprint and so cannot, by this logic alone, distinguish independent discovery from copying.

Matters to this vault as a recurring, load-bearing test for adjudicating bipartite-hop pairings between citation-tracing claims. First named and applied in [[observation-copy-fingerprint-logic-explains-why-kwakernaak-1977-trail-cannot-date-song-jians-acquisition]] (2026-09-24), contrasting [[claim-ansari-2026-contamination-inheritance-citation-error-propagates-across-models|Ansari's Contamination Inheritance]] (which has a fingerprint, n=1) against the Kwakernaak-1977 citation trail (which has none). Applied a second time in [[observation-chainqueen-ansari-contamination-inheritance-cosine-085-pairing-is-hedged-bridge]] (2026-10-10), this time contrasting Ansari's single fingerprint against a case that doesn't need one at all — ChainQueen's citation to Sulsky/Schreyer, independently corroborated outside the citation chain — sharpening the test's scope: it matters only when citation-chain evidence is the *sole* evidence available.

Applied a third time in [[observation-ansari-griewank-contamination-inheritance-cosine-086-pairing-is-embedding-false-friend]] (2026-10-16), against DiffTaichi's citation of Griewank & Walther (2008). Unlike the ChainQueen case, no asymmetry-in-evidence survives to hedge over here: DiffTaichi's citation is to an openly checkable textbook, needs no corroborating second leg, and so carries no fingerprint to assess at all — yielding this cluster's first clean false-friend verdict rather than another hedge.

Ansari's own paper names the matching, unperformed capability directly: "training-data audits, version-controlled corpus tracking, and citation genealogy mapping" (§4.8.1) — the LLM-training-era cousin of the same method.

## References
- [[observation-copy-fingerprint-logic-explains-why-kwakernaak-1977-trail-cannot-date-song-jians-acquisition]]
- [[observation-chainqueen-ansari-contamination-inheritance-cosine-085-pairing-is-hedged-bridge]]
- [[claim-simkin-roychowdhury-2002-identical-citation-misprints-are-copy-fingerprints-implying-about-20-percent-of-citers-read-the-original]]
- [[claim-ansari-2026-contamination-inheritance-citation-error-propagates-across-models]]
- Captures: 10-inbox/raw/2026-09-24-bipartite-two-things-this-vault-knows-in-different-kwakernaak-ansari.md, 10-inbox/raw/2026-10-07-bipartite-ml-ai-computing-ansari-2026-traces-one-case-of.md