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The Erdős–Szemerédi Sum–Product Conjecture over ℝ

AI-resolved

Posed by Paul Erdős / Endre Szemerédi · 1983 · additive combinatorics · resolved 2026

The problem

For a finite set A ⊂ ℝ, must max(|A+A|, |A·A|) be at least |A|^{2−o(1)}? Erdős and Szemerédi (1983) conjectured yes; the best known lower bounds were |A|^{4/3+o(1)}.

History & significance

One of additive combinatorics' central drivers, feeding into incidence geometry and the polynomial method. Elekes's connection to unit distances made it a cousin of Erdős's geometry problems.

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