On Sumsets and Spectral Gaps

dc.creatorCroot, Ernie
dc.creatorSchoen, Tomasz
dc.date2007-08-02
dc.date2007-11-28
dc.date.accessioned2026-07-07T08:45:12Z
dc.date.available2026-07-07T08:45:12Z
dc.descriptionIt is well known that if S is a subset of the integers mod p, and if the second-largest Fourier coefficient is ``small'' relative to the largest coefficient, then the sumset S+S is much larger than S. We show in the present paper that if instead of having such a large ``spectral gap'' between the largest and second-largest Fourier coefficients, we had it between the kth largest and the (k+1)st largest, the same thing holds true, namely that |S+S| is appreciably larger than |S|. Well, we only do this for k < (log p)/(log 4). We also obtain analogous results for repeated sumsets S+S+...+S, and it turns out that the more terms one includes, the larger the index k that can be used.
dc.descriptionA few typos have been corrected. Also theorem 2 in the last draft should have said ``t >= 3'', not ``t >= 2''
dc.identifierhttps://arxiv.org/abs/0708.0381
dc.identifierhttp://arxiv.org/abs/0708.0381
dc.identifier.urihttp://salesiana.dossiersoluciones.com/handle/123456789/142897
dc.subjectCombinatorics
dc.subjectNumber Theory
dc.subject05D99
dc.titleOn Sumsets and Spectral Gaps
dc.typetext

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