Deletion Formulas for Equivariant Kazhdan–Lusztig Polynomials of Matroids

We study equivariant Kazhdan-Lusztig (KL) and Z-polynomials of matroids. We formulate an equivariant generalization of a result by Braden and Vysogorets that relates the equivariant KL and Z-polynomials of a matroid with those of a single-element deletion. We also discuss the failure of equivariant \gamma-positivity for the Z-polynomial. As an application of our main result, we obtain a formula for the equivariant KL polynomial of the graphic matroid gotten by gluing two cycles. Furthermore, we compute the equivariant KL polynomials of all matroids of corank 2 via valuations. This provides an application of the machinery of Elias et al. to corank 2 matroids, and it extends results of Ferroni and Schr" oter.