Speaker
Anna Weigandt: University of Minnesota
Abstract
“Bumpless pipe dreams are combinatorial objects in bijection with alternating sign matrices. Double Grothendieck polynomials can be expressed as weighted sums over bumpless pipe dreams, a perspective that has led to many advances in the combinatorics of Schubert calculus and integrable systems. We introduce symplectic bumpless pipe dreams and present an analogous formula for symplectic Grothendieck polynomials, which represent the equivariant $K$–theoretic classes of $\mathrm{Sp}_{2n}$–orbit closures in the flag variety. To prove this result, we construct an analogue of Lascoux’s inflation on these objects, providing a combinatorial realization of the symplectic transition equations that appear in work of the first author, Marberg, and Pawlowski.
This is joint work with Zachary Hamaker.”