On the degree of Grothendieck polynomials

Abstract: A beautiful degree formula for the Grothendieck polynomials was recently given by Pechenik, Speyer, and Weigandt (2021). We provide an alternative proof of their degree formula, utilizing the climbing chain model for Grothendieck polynomials introduced by Lenart, Robinson, and Sottile (2006). Moreover, for any term order satisfying $x_1<x_2<\cdots<x_n$ we present the leading monomial of each homogeneous components of the Grothendieck polynomial $\mathfrak{G}_w(x_1,\ldots,x_n)$, confirming a conjecture of Hafner (2022). We conclude with a conjecture for the leading monomials of the homogenegous components of $\mathfrak{G}_w(x_1,\ldots,x_n)$ in any term order satisfying $x_1>x_2>\cdots>x_n$.