Antonio Pedro Ramos examines point-evaluation bounds for integrable functions of spherical exponential type in the multivariable Paley–Wiener space. Radial extremizers connect the problem to a weighted space in one variable. The talk establishes a third-order linear differential equation with polynomial coefficients in every dimension, extending the previously known odd-dimensional result. It also develops interpolation and reciprocal identities using the extremizer’s zeros. The research is joint work with Felipe Gonçalves and Danylo Radchenko.

Leonid Berlyand discusses mathematical models for the onset of cell motion driven by myosin contraction. A two-dimensional free-boundary PDE model links cell-shape evolution to diffusion and Keller–Segel-type transport. The talk examines linear stability, a stability-determining eigenvalue and the way nonlinear diffusion changes the bifurcation from supercritical to subcritical. It also considers the curvature of the bifurcation curve, connections to bistability, and the role of non-self-adjoint operators. An example illustrates why a spectral gap alone need not guarantee stability. This is an in-person Analysis of Fluids and Related Topics seminar at Princeton.

Ivo Düntsch presents an algebraic treatment of the ternary betweenness relation familiar from geometry. The talk introduces betweenness algebras and the logic K^#, which uses two complementary binary modalities. Its algebraic models are Boolean algebras equipped with two binary modal operators linked by a connecting condition. This extends unary mixed logic and increases the expressive power of classical modal logic. The presentation develops properties of these structures from joint work with R. Gruszczyński and P. Menchón at Nicolaus Copernicus University. Online via Chapman University GALAI Zoom. Wednesday 30 September 2026, 14:30 PDT (America/Los_Angeles; UTC−7). Use the current Zoom link at the top of the organizer’s seminar page. Organized by Peter Jipsen at Chapman’s Center of Excellence in Computation, Algebra and Topology. The usual seminar slot ends at 15:45; no event-specific end time is given. This listing advertises the remote option.