# Pure Maths Colloquium: Tuomas Orponen

This talk is part of the Pure Maths Colloquium at the University of St Andrews. Check out our upcoming talks at https://theran.lt/pure-colloquium/.

Where: | Zoom 812 4618 4775 |

When: | Nov 4 2021 @ 16.00 |

Video: | Link (internal) |

Speaker: | Tuomas Orponen Jyväskylän yliopisto |

Title: | Some products of recent work on sum-products |

If \(A,B,C\) are three finite sets in a field, under what assumptions can we find a point \(c\) in \(C\) such that \(A + cB\) is much bigger than \(A\)? This is a variant of the Erdős-Szemerédi sum-product problem. I will briefly survey the problem in a number of fields. Then I will focus on the \(\delta\)-discretised version of the problem on the real line. This version is the most relevant one for fractal geometers.