Seminar: Murat Can Aşkaroğulları - Leibniz prop is a crossed presimplicial algebra (Jan 23, 2026)

https://www.turkmath.org/beta/seminer.php?id_seminer=4169

Speaker: Murat Can Aşkaroğulları (Gebze Teknik Üniversitesi)

Title: Leibniz prop is a crossed presimplicial algebra

Time: January 23, Friday, 2026 at 13:30

Place: Feza Gürsey Center for Physics and Mathematics

Abstract: Let $s(n)$ denote the sum of proper divisors of a positive integer $n$. In 1992, Erd\H{o}s, Granville, Pomerance, and Spiro conjectured that if $\mathcal{A}$ is a set of integers with asymptotic density zero, then the preimage set $s^{-1}(\mathcal{A})$ also has asymptotic density zero. In this talk, we will discuss the verification of this conjecture when $\mathcal{A}$ is the set of integers with missing digits (also known as ellipsephic integers) by giving a quantitative estimate on the size of the set $s^{-1}(\mathcal{A})$. This talk is based on joint work with Giulia Cesana, C'{e}cile Dartyge, Charlotte Dombrowsky, Paul Pollack, and Lola Thompson.