
arXiv: 1606.03468
We show that, for a finite set $A$ of real numbers, the size of the set$$\frac{A+A}{A+A} = \left\{ \frac{a+b}{c+d} : a,b,c,d \in A, c+d \neq 0 \right \}$$is bounded from below by$$\left|\frac{A+A}{A+A} \right| \gg \frac{|A|^{2+1/4}}{|A / A|^{1/8} \log |A|}.$$This improves a result of Roche-Newton (2016).
Permutations, words, matrices, Other combinatorial number theory, FOS: Mathematics, additive combinatorics, Mathematics - Combinatorics, Combinatorics (math.CO), Erdős problems and related topics of discrete geometry
Permutations, words, matrices, Other combinatorial number theory, FOS: Mathematics, additive combinatorics, Mathematics - Combinatorics, Combinatorics (math.CO), Erdős problems and related topics of discrete geometry
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