Konferanser ved UiO

Positroids are a class of matroids that were introduced by Postnikov in 2006 that index a certain stratification of the totally non-negative Grassmannian. These matroids are famously in bijection with a ¡°zoo¡± of combinatorial objects including Grassmann necklaces and plabic graphs. We introduce a new family of positroids called rook matroids that arise from restricted rook placements on a skew shaped board and discuss it in terms of this zoo. We highlight the transversal structure of rook matroids and the slightly mysterious relationship they share with lattice path matroids. This is joint work with Per Alexandersson and ongoing work with Irem Portakal and Akiyoshi Tsuchiya. 

Positive geometry is a recent branch of mathematical physics which present exciting connections with real, complex and tropical algebraic geometry.

In this talk, we introduce the topic by developing the positive geometry of del Pezzo surfaces and their moduli spaces. 

We will analyze their connected components, likelihood equations and scattering amplitudes. 

The talk is based on joint work with Early, Geiger, Sturmfels and Yun. 

Abstract:  I will introduce a certain configuration space associated with a graph, and compute its cohomology ring.  It turns out to be related to internal zonotopal algebras, which were introduced in the context of approximation theory and show up in many different contexts.

This is joint work with Colin Crowley, Galen Dorpalen-Barry, and Andre Henriques.