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Main Authors: Fan, Neil J. Y., Guo, Peter L., Xiong, Rui
Format: Preprint
Published: 2023
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Online Access:https://arxiv.org/abs/2309.00467
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author Fan, Neil J. Y.
Guo, Peter L.
Xiong, Rui
author_facet Fan, Neil J. Y.
Guo, Peter L.
Xiong, Rui
contents Knutson and Zinn-Justin recently found a puzzle rule for the expansion of the product $\mathfrak{G}_{u}(x,t)\cdot \mathfrak{G}_{v}(x,t)$ of two double Grothendieck polynomials indexed by permutations with separated descents. We establish its triple Schubert calculus version in the sense of Knutson and Tao, namely, a formula for expanding $\mathfrak{G}_{u}(x,y)\cdot \mathfrak{G}_{v}(x,t)$ in different secondary variables. Our rule is formulated in terms of pipe puzzles, incorporating both the structures of bumpless pipe dreams and classical puzzles. As direct applications, we recover the separated-descent puzzle formula by Knutson and Zinn-Justin (by setting $y=t$) and the bumpless pipe dream model of double Grothendieck polynomials by Weigandt (by setting $v=\operatorname{id}$ and $x=t$). Moreover, we utilize the formula to partially confirm a positivity conjecture of Kirillov about applying a skew operator to a Schubert polynomial.
format Preprint
id arxiv_https___arxiv_org_abs_2309_00467
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle Bumpless pipe dreams meet Puzzles
Fan, Neil J. Y.
Guo, Peter L.
Xiong, Rui
Combinatorics
Algebraic Geometry
Knutson and Zinn-Justin recently found a puzzle rule for the expansion of the product $\mathfrak{G}_{u}(x,t)\cdot \mathfrak{G}_{v}(x,t)$ of two double Grothendieck polynomials indexed by permutations with separated descents. We establish its triple Schubert calculus version in the sense of Knutson and Tao, namely, a formula for expanding $\mathfrak{G}_{u}(x,y)\cdot \mathfrak{G}_{v}(x,t)$ in different secondary variables. Our rule is formulated in terms of pipe puzzles, incorporating both the structures of bumpless pipe dreams and classical puzzles. As direct applications, we recover the separated-descent puzzle formula by Knutson and Zinn-Justin (by setting $y=t$) and the bumpless pipe dream model of double Grothendieck polynomials by Weigandt (by setting $v=\operatorname{id}$ and $x=t$). Moreover, we utilize the formula to partially confirm a positivity conjecture of Kirillov about applying a skew operator to a Schubert polynomial.
title Bumpless pipe dreams meet Puzzles
topic Combinatorics
Algebraic Geometry
url https://arxiv.org/abs/2309.00467