Department of

# Mathematics

Seminar Calendar
for events the day of Thursday, January 14, 2021.

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Thursday, January 14, 2021

3:00 pm in Zoom,Thursday, January 14, 2021

#### A crystal for stable Grothendieck polynomials

###### Jianping Pan   [email] (UC Davis)

Abstract: We construct a type A crystal, which we call the $\star$-crystal, whose character is the stable Grothendieck polynomials for fully-commutative permutations. This crystal is a K-theoretic generalization of Morse-Schilling crystal on decreasing factorizations. Using the residue map, we showed that this crystal intertwines with the crystal on set-valued tableaux given by Monical, Pechenik and Scrimshaw. We also proved that this crystal is isomorphic to that of pairs of semistandard Young tableaux using a newly defined insertion called the $\star$ -insertion. The insertion offers a combinatorial interpretation to the Schur positivity of the stable Grothendieck polynomials for fully-commutative permutations. Furthermore, the $\star$ -insertion has interesting properties in relation to row Hecke insertion and the uncrowding algorithm. This is joint work with Jennifer Morse and Anne Schilling. Please email Colleen at cer2 (at) illinois (dot) edu for the Zoom ID and password.