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In their work on the infinite flag variety, Lam, Lee, and Shimozono (2018) introduced objects called bumpless pipe dreams and used them to give a formula for double Schubert polynomials. We extend this formula to the setting of K-theory,…

Combinatorics · Mathematics 2020-03-17 Anna Weigandt

Schubert polynomials are distinguished representatives of Schubert cycles in the cohomology of the flag variety. In the spirit of Bergeron and Sottile, we use the Bruhat order to give $(n-1)!$ different combinatorial formulas for the…

Combinatorics · Mathematics 2024-07-09 Tianyi Yu

Bumpless pipe dreams (BPDs) are combinatorial objects used in the study of Schubert and Grothendieck polynomials. Weigandt recently introduced a co-BPD object associated to each BPD and used them to give an analogue to the change of bases…

Combinatorics · Mathematics 2026-01-01 Joshua Arroyo , Adam Gregory

In their study of infinite flag varieties, Lam, Lee, and Shimozono (2021) introduced bumpless pipe dreams in a new combinatorial formula for double Schubert polynomials. These polynomials are the TxT-equivariant cohomology classes of matrix…

Combinatorics · Mathematics 2025-09-03 Patricia Klein , Anna Weigandt

Schubert polynomials are polynomial representatives of Schubert classes in the cohomology of the complete flag variety and have a combinatorial formulation in terms of bumpless pipe dreams. Quantum double Schubert polynomials are polynomial…

Combinatorics · Mathematics 2025-02-12 Tuong Le , Shuge Ouyang , Leo Tao , Joseph Restivo , Angelina Zhang

Pipedreams and bumpless pipedreams are two combinatorial models that compute double Grothendieck polynomials. While studying matrix Schubert varieties, Pechenik, Speyer, and Weigandt defined a permutation statistic$\mathsf{rajcode}(\cdot)$…

Combinatorics · Mathematics 2026-05-26 Xuanying Han , Sophie C. C. Sun

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…

Combinatorics · Mathematics 2025-10-15 Neil J. Y. Fan , Peter L. Guo , Rui Xiong

Kazhdan-Lusztig ideals, a family of generalized determinantal ideals investigated in [Woo-Yong '08], provide an explicit choice of coordinates and equations encoding a neighbourhood of a torus-fixed point of a Schubert variety on a type A…

Combinatorics · Mathematics 2012-07-31 Alexander Woo , Alexander Yong

Knutson and Miller (2005) established a connection between the anti-diagonal Gr\"obner degenerations of matrix Schubert varieties and the pre-existing combinatorics of pipe dreams. They used this correspondence to give a…

Commutative Algebra · Mathematics 2023-01-19 Patricia Klein

We construct a bijection between marked bumpless pipedreams with reverse compatible pairs, which are in bijection with not-necessarily-reduced pipedreams. This directly unifies various formulas for Grothendieck polynomials in the…

Combinatorics · Mathematics 2024-07-26 Daoji Huang , Mark Shimozono , Tianyi Yu

The geometric naturality of Schubert polynomials and their combinatorial pipe dream representations was established by Knutson and Miller (2005) via antidiagonal Gr\"obner degeneration of matrix Schubert varieties. We consider instead…

Combinatorics · Mathematics 2022-03-25 Zachary Hamaker , Oliver Pechenik , Anna Weigandt

We give a new proof that three families of polynomials coincide: the double Schubert polynomials of Lascoux and Sch\"utzenberger defined by divided difference operators, the pipe dream polynomials of Bergeron and Billey, and the equivariant…

Combinatorics · Mathematics 2022-02-08 Allen Knutson

In [KU23] were introduced hybrid pipe dreams interpolating between classic and bumpless pipe dreams, each hybridization giving a different formula for double Schubert polynomials. A bijective proof was given (following [GH23]) of the…

Combinatorics · Mathematics 2025-09-03 Allen Knutson , Paul Zinn-Justin

We investigate the longstanding 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. Sch\"{u}tzenberger (1982) serve…

Combinatorics · Mathematics 2019-10-23 Oliver Pechenik , Dominic Searles

Pipedreams are combinatorial objects that compute Grothendieck polynomials. We introduce a new combinatorial object that naturally recast the pipedream formula. From this, we obtain the first direct combinatorial formula for the top degree…

Combinatorics · Mathematics 2025-02-12 Chen-An Chou , Tianyi Yu

We study random permutations arising from reduced pipe dreams. Our main model is motivated by Grothendieck polynomials with parameter $\beta=1$ arising in K-theory of the flag variety. The probability weight of a permutation is proportional…

Probability · Mathematics 2025-04-17 Alejandro H. Morales , Greta Panova , Leonid Petrov , Damir Yeliussizov

In this paper, we establish a new geometric setting for bumpless pipe dreams and double Schubert polynomials. Building on the notion of bumpless pipe dream fragments, we define clan polynomials as their weight generating functions. It turns…

Combinatorics · Mathematics 2025-11-25 Yiming Chen , Neil J. Y. Fan , Rui Xiong , Ming Yao

We develop a family of new combinatorial models for key polynomials. It is similar to the hybrid pipe dream model for Schubert polynomials defined recently by Knutson and Udell.

Combinatorics · Mathematics 2025-10-15 Yihan Xiao , Rui Xiong , Haofeng Zhang

We give bijective proofs of Monk's rule for Schubert and double Schubert polynomials computed with bumpless pipe dreams. In particular, they specialize to bijective proofs of transition and cotransition formulas of Schubert and double…

Combinatorics · Mathematics 2020-10-29 Daoji Huang

We give an algebra-combinatorial constructions of (noncommutative) generating functions of double Schubert and double $\beta$-Grothendieck polynomials corresponding to the full flag varieties associated to the Lie groups of classical types…

Combinatorics · Mathematics 2015-04-08 A. N. Kirillov
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