Problem detail · source-aware
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Denjoy's 1932 theorem says a $C^{1+\mathrm{bv}}$ circle diffeomorphism with irrational rotation number has no wandering interval. Whether it is sharp in regularity: for every concave modulus of continuity $\omega$ weaker than Lipschitz, there is a $C^{1+\omega}$ circle diffeomorphism with irrational rotation number and a wandering interval. The case $\omega(t) = t\log(1/t)$ settles an open problem going back to Herman's 1979 work, which had constructions only for $\omega(t) = t\log(1/t)^{1+\varepsilon}$.
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The AI use section says the author prompted GPT-5.6 Sol Ultra to construct a Denjoy example for the modulus $t\log(1/t)$, which is the corollary settling Herman's case, and used Claude Fable 5 to search for errors.
Provider: unknown · Prompt public: unknown · Independence: unknown
arXiv preprint, not yet peer-reviewed.
Correctness: unknown · statement fidelity: unaudited · peer review: none
VibeMathed reports this item as resolved. VibeMath preserves that report as a source assertion and has not independently authored a plain-language mathematical explanation.
Source-reported tools: construction.
Independent: unknown · difference confidence: 0
VibeMath has not independently audited the mathematical statement, proof, or novelty claim.