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SUMMARY:Difference sets and nonnegative exponential sums - Máté Matolcsi
DTSTART:20100217T140000Z
DTEND:20100217T150000Z
UID:TALK22147@talks.cam.ac.uk
CONTACT:Boris Bukh
DESCRIPTION:Given a prescribed subset R of some Abelian group\, what is th
 e maximal cardinality of a set A such that the difference set A-A lies in 
 R? Several problems from strikingly different parts of mathematics fit int
 o this general setting\, including sphere-packings\, number theoretical pr
 oblems and mutually unbiased bases. In this talk I will describe a general
  method (due to Delsarte) involving nonnegative exponential sums which lea
 ds to upper bounds on the cardinality (or density) of such sets A. Possibl
 e applications will be mentioned. Some of the material is joint work with 
 Imre Z. Ruzsa.\n
LOCATION:MR12\, CMS
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