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Let F in Complex[x,y,z] be a constant-degree polynomial, and let A,B,C be sets of complex numbers with |A|=|B|=|C|=n. We show that F vanishes on at most O(n^{11/6}) points of the Cartesian product A x B x C (where the constant of proportionality depends polynomially on the degree of F), unless F has a special group-related form. This improves a theorem of Elekes and Szabo [ES12], and generalizes a result of Raz, Sharir, and Solymosi [RSS14a]. The same statement holds over R. When A, B, C have different sizes, a similar statement holds, with a more involved bound replacing O(n^{11/6}).
This result provides a unified tool for improving bounds in various Erdos-type problems in combinatorial geometry, and we discuss several applications of this kind.
@InProceedings{raz_et_al:LIPIcs.SOCG.2015.522,
author = {Raz, Orit E. and Sharir, Micha and de Zeeuw, Frank},
title = {{Polynomials Vanishing on Cartesian Products: The Elekes-Szab\'{o} Theorem Revisited}},
booktitle = {31st International Symposium on Computational Geometry (SoCG 2015)},
pages = {522--536},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-939897-83-5},
ISSN = {1868-8969},
year = {2015},
volume = {34},
editor = {Arge, Lars and Pach, J\'{a}nos},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.SOCG.2015.522},
URN = {urn:nbn:de:0030-drops-51031},
doi = {10.4230/LIPIcs.SOCG.2015.522},
annote = {Keywords: Combinatorial geometry, incidences, polynomials}
}