Babai and Frankl's Oddtown Question for Composite Moduli
resolvedconfidence 70%
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Precise statement
An $\ell$-Oddtown is a family of subsets of an $n$-element set whose set sizes are not divisible by $\ell$ while all pairwise intersection sizes are. Berlekamp and Graver showed the maximum size is $n$ for prime $\ell$, Babai and Frankl extended this to prime powers and asked whether $n$ still holds for other moduli, a question open even for $\ell = 6$. Bukh, Chao and Zheng answer it negatively with an explicit superlinear construction, complemented by new upper bounds.
The source statement is reproduced for indexing with attribution. Mathematical correctness requires domain-expert or mechanical review. VibeMath has not independently audited statement
fidelity, correctness, priority, or novelty.
What AI did
GPT-5.6 Sol
The lower-bound construction in Section 2 was first proposed by GPT-5.6 Sol in response to prompts from the authors; the upper-bound results were obtained without AI assistance. (The disclosure was added in the paper's second version.)
VibeMathed reports this item as resolved. VibeMath preserves that report as a source assertion and has not independently authored a plain-language mathematical explanation.
Known method families
construction (source-reported)
Source-reported tools: construction.
Independent: unknown · difference confidence: 0
What remains uncertain
VibeMath has not independently audited the mathematical statement, proof, or novelty claim.
VibeMath has not independently verified the mathematical claim.
AI-attempt independence and training-data exposure are unknown unless explicitly documented.
VibeMath has not independently audited the mathematical statement, proof, or novelty claim.