Thursday, April 14, 2022 - 11:00 to 12:00

427 Thackeray Hall

### Abstract or Additional Information

A theorem of Brion shows that the Schubert structure constants in the K theory ring of flag manifolds satisfy a positivity property. I will discuss a similar positivity property in the quantum K theory ring of a Grassmann manifold. The key ingredients are: the `quantum = classical' statement of Buch, Chaput, Perrin, and the speaker, and the cohomological properties of fibers of projections from Richardson varieties, and from codimension 1 subvarieties in Richardson varieties. This is joint work with A. Buch, P.E. Chaput and N. Perrin.