An equivariant quantum Pieri rule for the Grassmannian on cylindric shapes

Anna Bertiger, Dorian Ehrlich, Elizabeth Milićević, Kaisa Taipale

Published 2020-10-29Version 1

The quantum cohomology ring of the Grassmannian is determined by the quantum Pieri rule for multiplying by Schubert classes indexed by row or column-shaped partitions. We provide a direct equivariant generalization of Postnikov's quantum Pieri rule for the Grassmannian in terms of cylindric shapes. The equivariant terms in this Graham-positive rule simply encode the positions of all possible addable boxes within one cylindric skew diagram. As such, unlike the earlier equivariant quantum Pieri rule of Huang and Li and known equivariant quantum Littlewood-Richardson rules, our formula does not require any calculations in a different Grassmannian or two-step flag variety.