Brezis's Open Problem 5.6 on Universal Fourier Summation
partialconfidence 70%
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Precise statement
Does a universal summation process recover the degree of a circle map from its Fourier moduli, that is, does $\sum_n \sigma_{n,\varepsilon} n |\hat f(n)|^2 \to \deg f$ hold for Holder maps below the threshold? No. For every $0 < \alpha < 1/3$ there is an $f \in C^{0,\alpha}(S^1;S^1)$ for which the sum fails to converge to $\deg f$, answering Open Problem 5.6 from Brezis's list of favourite open problems negatively for all $p > 3$. The endpoint $C^{0,1/3}$ is left unresolved.
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What AI did
ChatGPT
The disclosure states that ChatGPT generated preliminary drafts of the proofs in the manuscript. The author then verified each argument in detail, revised the proofs where necessary, checked the cited sources, determined the final formulation of all results, and takes sole responsibility for the content.
Single-author arXiv preprint; the construction combines degree-zero quotients of Blaschke factors with a Baire category argument. Not yet peer-reviewed.