Oriented and Valuated Delta Matroids from Stable Polynomials

Abstract

Stable polynomials are the natural multivariate generalization of real rooted univariate polynomials. While their definition is purely algebraic in nature, they have deep connections to combinatorics. One such connection is the support theorem proved by Brändén in 2007, showing that the support of any stable polynomial is a jump system, and hence that the support of any multiaffine stable polynomial is a $Δ$-matroid. In this work, we generalize this result, showing that coefficients of multiaffine real stable polynomials give rise to oriented $Δ$-matroids, and coefficients of multiaffine stable polynomials over Puiseux series give rise to valuated $Δ$-matroids.