Sumsets of sparse sets

نویسندگان

  • Arturas Dubickas
  • Paulius Sarka
چکیده

Let σ be a constant in the interval (0, 1), and let A be an infinite set of positive integers which contains at least c1x σ and at most c2x σ elements in the interval [1, x] for some constants c2 > c1 > 0 independent of x and each x ≥ x0. We prove that then the sumset A + A has more elements than A (counted up to x) by a factor c(σ) √ log x/ log log x for x large enough. An example showing that this function cannot be greater than ε log x is also given. Another example shows that there is a set of positive integers A which contains at least x and at most x elements in [1, x] such that A + A is greater than A only by a constant factor. The proof of the main result is based on an effective version of Freiman’s theorem due to Mei-Chu Chang.

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عنوان ژورنال:
  • Periodica Mathematica Hungarica

دوره 64  شماره 

صفحات  -

تاریخ انتشار 2012