%APechenik, Oliver%ASearles, Dominic%Anull Ed.%BJournal Name: International Mathematics Research Notices; Journal Volume: 2019; Journal Issue: 10
%D2017%I
%JJournal Name: International Mathematics Research Notices; Journal Volume: 2019; Journal Issue: 10
%K
%MOSTI ID: 10216216
%PMedium: X
%TDecompositions of Grothendieck Polynomials
%XAbstract We investigate the long-standing problem of finding a combinatorial rule for the Schubert structure constants in the $K$-theory of flag varieties (in type $A$). The Grothendieck polynomials of A. Lascoux–M.-P. Schützenberger (1982) serve as polynomial representatives for $K$-theoretic Schubert classes; however no positive rule for their multiplication is known in general. We contribute a new basis for polynomials (in $n$ variables) which we call glide polynomials, and give a positive combinatorial formula for the expansion of a Grothendieck polynomial in this basis. We then provide a positive combinatorial Littlewood–Richardson rule for expanding a product of Grothendieck polynomials in the glide basis. Our techniques easily extend to the $\beta$-Grothendieck polynomials of S. Fomin–A. Kirillov (1994), representing classes in connective $K$-theory, and we state our results in this more general context.
%0Journal Article