Séminaire Lotharingien de Combinatoire, 84B.38 (2020), 12 pp.
Takahiro Nagaoka and Akiko Yazawa
Strict Log-Concavity of the Kirchhoff Polynomial and Its Applications
Anari, Gharan, and Vinzant showed that the basis generating functions for all matroids are log-concave.
In this paper, we show that Kirchhoff polynomials, i.e. the basis generating functions for simple graphic matroids, are strictly log-concave.
Our key observation is that the Kirchhoff polynomial of a complete graph can be seen as the irreducible relative invariant of a certain prehomogeneous vector space.
Furthermore, we prove that an algebra associated to a graphic matroid satisfies the strong Lefschetz property and Hodge-Riemann bilinear relation at degree one.
Received: November 20, 2019.
Accepted: February 20, 2020.
Final version: April 30, 2020.
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