DiffTaichi's Griewank citation (Feb 2020) predates ChatGPT's public launch (Nov 2022) by nearly three years, foreclosing an LLM-contamination explanation for that specific citation

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DiffTaichi — the paper in the ChainQueen/Bolliger/DiffTaichi cluster that names Andreas Griewank by name — carries the timestamp arXiv:1910.00935v3, 14 Feb 2020. OpenAI's own announcement page states: "November 30, 2022" as the date it introduced ChatGPT. DiffTaichi's text, including its Griewank citation, existed roughly two years and nine months before ChatGPT existed at all.

This closes, for DiffTaichi specifically, an unchecked lead flagged in the 2026-10-07 sibling capture on the adjacent ChainQueen/Bolliger/DiffTaichi cluster: whether any paper in the cluster citing Griewank could reflect an Ansari-style training-corpus contamination artifact rather than a direct, intentional citation. For DiffTaichi, the answer is no — not because the mechanism was checked and absent, but because the citing text predates the technology Ansari's mechanism requires. This does not extend to the rest of the cluster: Bolliger et al. (2025) postdates ChatGPT's launch and has not been checked for fabricated or contaminated citations; nothing here speaks to it.

The finding is a date-based disconfirmation, not an inference from the copy-fingerprint test applied elsewhere in this cluster (see observation-ansari-griewank-contamination-inheritance-cosine-086-pairing-is-embedding-false-friend) — it would hold even if that pairing's verdict had gone the other way, since it rests only on two dates, not on any judgment about citation shape.