Time: 16:30-18:00

Location: Mondi 3 / Central Building

Speaker 1: Ksenia Khudiakova (Barton & Maas group)

Title: How Background Fluctuations Reshape Mutation Fates

Abstract: In a population under quadratic stabilizing selection, mutations don’t have fixed destinies. Instead, depending on the population's current state, their fitness effect changes magnitude or even sign. This process can be represented as commuting through the fitness distribution as the background trait value wanders. This induces a dynamic distribution of fitness effects (DFE) where some mutations remain permanently neutral or harmful, while others frequently switch sign. I present a semi-analytical description of these trajectories, quantifying how often and how far mutations travel in the DFE, and show how this mobility shapes evolutionary equilibrium.

Speaker 2: Alexandr Grebennikov (Kwan group)

Title: No-(k+1)-in-line problem for large constant k

Abstract: How many points can be placed in an n×n grid so that every (affine) line contains at most k points? We prove that for n ≥ k ≥ 10^37, the maximum number of points is exactly kn. Our proof uses a probabilistic construction based on iterative applications of the Lovász Local Lemma. Joint work with Matthew Kwan.