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Ordered Variable Word theorem: first-order part announced as determined (Patey, with Claude Opus 5.5)

The gist

On October 20, 2026, Ludovic Patey posted on arXiv an answer to an open question in mathematical logic about the Ordered Variable Word theorem, with a core lemma proved by Claude Opus 5.5.

DiscoverIA status on October 24, 2026: not evaluated, meaning no third-party evaluation found.

Status detailsDetails

AI draft, not reviewedWhat has not been reviewed?

Text written by an AI (DiscoverIA pipeline), on . The status and its sources come from the registry; only the explanatory text has not been reviewed. A reported error is corrected, then the text is reviewed.

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Cite this entry

A single status snapshot since Oct 24, 2026: a citation always points to a dated snapshot.

Cite snapshot 1, Oct 24, 2026

APA citation with the dated link

DiscoverIA. (2026, October 24). Ordered Variable Word theorem: first-order part announced as determined (Patey, with Claude Opus 5.5) [Status: Not evaluated, snapshot 1]. DiscoverIA registry. https://discoveria.ai/entry/patey-mots-variables-ordonnes-2026-10-20#releve-1

BibTeX @misc, key discoveria-patey-mots-variables-ordonnes-2026-10-20-r1

@misc{discoveria-patey-mots-variables-ordonnes-2026-10-20-r1,
  author       = {{DiscoverIA}},
  title        = {Ordered Variable Word theorem: first-order part announced as determined (Patey, with Claude Opus 5.5)},
  howpublished = {DiscoverIA registry, entry patey-mots-variables-ordonnes-2026-10-20},
  note         = {Status “Not evaluated”, snapshot 1, recorded on October 24, 2026. New result},
  year         = {2026},
  url          = {https://discoveria.ai/entry/patey-mots-variables-ordonnes-2026-10-20#releve-1},
  urldate      = {2026-10-24}
}

Dated link opens this snapshot in the history

https://discoveria.ai/entry/patey-mots-variables-ordonnes-2026-10-20#releve-1

To understand ≈ 20 s reading time, estimated

What it changes

In reverse mathematics, the strength of a theorem is measured by the axioms needed to prove it. If the proof held, the Ordered Variable Word theorem, a result in combinatorics, would prove no more arithmetic statements than RCA_0 + BΣ^0_2, the base system RCA_0 extended by the collection principle BΣ^0_2. The author derives the same property for Chubb, Hirst and McNicholl's tree theorem for singletons, which would answer a long-standing open question.

What remains unclear

No third party has reviewed the proof yet, and it is not formalised.

For experts

Sources, method, key facts, status history, report an error

Status

Not evaluated

Recorded on · arxiv.org · abs/2610.27643

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What this status means

Source reading : Source read word for word (level 3 of 3)

The result is declared neither right nor wrong.

To move to “Under review”: a public review under way. To “Peer reviewed”: a journal publication or a review by named experts.

Full history

Proofs
préprint arXiv 2610.27643 (résumé et HTML lus)

Sources

  • Main sourcearxiv.org · abs/2610.27643page read word for word · consulted on Oct 24, 2026 · Lemma 3.13 was found by Claude Opus 5.5 (Anthropic).
  • Paperarxiv.org · html/2610.27643page read word for word · consulted on Oct 24, 2026 · The proof was completely rewritten by the author for clarity.

Method

The paper states that the theorem is Π^1_1-conservative over RCA_0 + BΣ^0_2. According to the paper, Claude Opus 5.5 proved the Π^0_1-extension lemma (Lemma 3.13), a core step, which Ludovic Patey rewrote completely; the original idea of the approach, proving Liu and Patey's weakly low basis theorem within a weak system with the techniques of Le Houérou, Patey and Yokoyama, was his. DiscoverIA status: not evaluated, meaning that no third-party evaluation has been found in the sources read. Set on October 24, 2026 from arxiv.org (page read, quotation checked word for word: “Lemma 3.13 was found by Claude Opus 5.5 (Anthropic).”).

Limits

DiscoverIA has not checked this result itself.

Key facts

Claimed by
Ludovic Patey, with Claude Opus 5.5 (Anthropic)
announced on Oct 20, 2026
Nature
new result
Field
Mathematics (mathematical logic / reverse mathematics)
Checked by
no verifier identified
Sources
2 : 2 read word for word
This entry
AI draft, not reviewed

Status history

Only one observation so far.

  1. 01

    First observation:Not evaluatedCurrent status

    arXiv preprint, not peer-reviewed or formalised; no third-party evaluation found

    Source: arxiv.orgread word for word

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