## Abstract

Let F ∈ C[x, y, s, t] be an irreducible constant-degree polynomial, and let A,B,C,D ⊂ C be finite sets of size n. We show that F vanishes on at most O(n^{8/3}) points of the Cartesian product A × B × C × D, unless F has a special group-related form. A similar statement holds for A,B,C,D of unequal sizes, with a suitably modified bound on the number of zeros. This is a four-dimensional extension of our recent improved analysis of the original Elekes–Szabó theorem in three dimensions. We give three applications: an expansion bound for three-variable real polynomials that do not have a special form, a bound on the number of coplanar quadruples on a space curve that is neither planar nor quartic, and a bound on the number of four-point circles on a plane curve that has degree at least five.

Original language | English |
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Pages (from-to) | 663-690 |

Number of pages | 28 |

Journal | Israel Journal of Mathematics |

Volume | 227 |

Issue number | 2 |

DOIs | |

State | Published - 1 Aug 2018 |

Externally published | Yes |

### Bibliographical note

Publisher Copyright:© 2018, Hebrew University of Jerusalem.