Raman Sanyal

The entropic discriminant

Abstract The entropic discriminant is a non-negative polynomial associated to a matrix. It arises in contexts ranging from statistics and linear programming to singularity theory and algebraic geometry. It describes the complex branch locus of the polar map of a real hyperplane arrangement, and it vanishes when the equations defining the analytic center of a linear program have a complex double root. We study the geometry of the entropic discriminant, and we express its degree in terms of the characteristic polynomial of the underlying matroid. Singularities of reciprocal linear spaces play a key role. In the corank-one case, the entropic discriminant admits a sum of squares representation derived from the discriminant of a characteristic polynomial of a symmetric matrix.

Ehrhart theory, modular flow reciprocity, and the Tutte polynomial

Given an oriented graph G, the modular flow polynomial

Theta rank, levelness, and matroid minors

{\phi_G(k)}

Deciding Polyhedrality of Spectrahedra

counts the number of nowhere-zero

Arithmetic of Marked Order Polytopes, Monotone Triangle Reciprocity, and Partial Colorings

{\mathbb{Z}_k}

Lipschitz polytopes of posets and permutation statistics

-flows of G. We give a description of the modular flow polynomial in terms of (open) Ehrhart polynomials of lattice polytopes. Using Ehrhart–Macdonald reciprocity we give a combinatorial interpretation for the values of