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arXiv · 1312.6438

Variations on the Sum-Product Problem

Brendan Murphy·Oliver Roche-Newton·Ilya D. Shkredov
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Abstract

This paper considers various formulations of the sum-product problem. It is shown that, for a finite set $A\subset{\mathbb{R}}$, $$|A(A+A)|\gg{|A|^{\frac{3}{2}+\frac{1}{178}}},$$ giving a partial answer to a conjecture of Balog. In a similar spirit, it is established that $$|A(A+A+A+A)|\gg{\frac{|A|^2}{\log{|A|}}},$$ a bound which is optimal up to constant and logarithmic factors. We also prove several new results concerning sum-product estimates and expanders, for example, showing that $$|A(A+a)|\gg{|A|^{3/2}}$$ holds for a typical element of $A$.

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Brendan Murphy, Oliver Roche-Newton, Ilya D. Shkredov. 2014-01-08. Variations on the Sum-Product Problem. https://arxiv.org/abs/1312.6438

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