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We generalize classical triangular Schubert puzzles to puzzles with convex polygonal boundary. We give these puzzles a geometric Schubert calculus interpretation and derive novel combinatorial commutativity statements, using purely…

Combinatorics · Mathematics 2024-06-13 Portia Anderson

We prove many simultaneous congruences mod 2 for elliptic and Hilbert modular forms among forms with different Atkin--Lehner eigenvalues. The proofs involve the notion of quaternionic $S$-ideal classes and the distribution of Atkin--Lehner…

Number Theory · Mathematics 2020-06-11 Kimball Martin

The monotone secant conjecture posits a rich class of polynomial systems, all of whose solutions are real. These systems come from the Schubert calculus on flag manifolds, and the monotone secant conjecture is a compelling generalization of…

Algebraic Geometry · Mathematics 2014-10-21 Nickolas Hein , Christopher J. Hillar , Abraham Martin del Campo , Frank Sottile , Zach Teitler

We present a procedure which enables the computation and the description of structures of isotropy subgroups of the group of complex orthogonal matrices with respect to the action of *congruence on Hermitian matrices. A key ingredient in…

Differential Geometry · Mathematics 2023-05-24 Tadej Starčič

The main goal of this paper is to extend two fundamental combinatorial results in Schubert calculus on flag manifolds from equivariant cohomology and $K$-theory to equivariant elliptic cohomology. The foundations of elliptic Schubert…

Combinatorics · Mathematics 2025-10-07 Cristian Lenart , Rui Xiong , Changlong Zhong

Let X be a symplectic or odd orthogonal Grassmannian parametrizing isotropic subspaces in a vector space equipped with a nondegenerate (skew) symmetric form. We prove a Giambelli formula which expresses an arbitrary Schubert class in…

Algebraic Geometry · Mathematics 2010-08-05 Anders S. Buch , Andrew Kresch , Harry Tamvakis

We characterize complete intersection matrix Schubert varieties, generalizing the classical result on one-sided ladder determinantal varieties. We also give a new proof of the F-rationality of matrix Schubert varieties. Although it is known…

Algebraic Geometry · Mathematics 2013-10-25 Jen-Chieh Hsiao

We recall the root game, introduced in an earlier paper, which gives a fairly powerful sufficient condition for non-vanishing of Schubert calculus on a generalised flag manifold G/B. We show that it gives a necessary and sufficient rule for…

Combinatorics · Mathematics 2007-05-23 Kevin Purbhoo

We study the toric degeneration of Weyl group translated Schubert divisors of a partial flag variety of Lie type A via Gelfand-Cetlin polytopes. We propose a conjecture that Schubert varieties of appropriate dimensions intersect…

Algebraic Geometry · Mathematics 2021-12-24 DongSeon Hwang , Hwayoung Lee , Jae-Hyouk Lee , Changzheng Li

We develop a canonical form for congruence of max plus symmetric matrices. We use the same canonical form to get results in the generalized eigenvector problem. We have also utilized the canonical form to find all symmetric matrices that…

Rings and Algebras · Mathematics 2024-10-17 Himadri Mukherjee , Askar Ali M

We compute the congruence class modulo 16 of the number of unique path partitions of $n$ (as defined by Olsson), thus generalising previous results by Bessenrodt, Olsson and Sellers [Ann. Combin. 13 (2013), 591-602].

Combinatorics · Mathematics 2018-02-06 Christian Krattenthaler

Many aspects of Schubert calculus are easily modeled on a computer. This enables large-scale experimentation to investigate subtle and ill-understood phenomena in the Schubert calculus. A well-known web of conjectures and results in the…

Algebraic Geometry · Mathematics 2013-08-16 Abraham Martin del Campo , Frank Sottile

We propose a combinatorial model for the Schubert structure constants of the complete flag manifold when one of the factors is Grassmannian.

Algebraic Geometry · Mathematics 2023-06-16 Sami H. Assaf

The coincidence problem for planar patterns with $N$-fold symmetry is considered. For the N-fold symmetric module with $N<46$, all isometries of the plane are classified that result in coincidences of finite index. This is done by…

Metric Geometry · Mathematics 2009-11-11 Peter A. B. Pleasants , Michael Baake , Johannes Roth

We prove two lemmata about Schubert calculus on generalized flag manifolds G/B, and in the case of the ordinary flag manifold GL_n/B we interpret them combinatorially in terms of descents, and geometrically in terms of missing subspaces.…

Combinatorics · Mathematics 2010-04-26 Allen Knutson

Let $p_2(n)$ denote the number of cubic partitions. In this paper, we shall present two new congruences modulo $11$ for $p_2(n)$. We also provide an elementary alternative proof of a congruence established by Chan. Furthermore, we will…

Number Theory · Mathematics 2017-02-14 Shane Chern , Manosij Ghosh Dastidar

We construct Koppelman formulas on manifolds of flags in $\C^N$ for forms with values in any holomorphic line bundle as well as in the tautological vector bundles and their duals. As an application we obtain new explicit proofs of some…

Complex Variables · Mathematics 2010-12-17 Håkan Samuelsson , Henrik Seppänen

If the flag curvature of a Finsler manifold reduces to sectional curvature, then locally either the Finsler metric is Riemannian, or the flag curvature is isotropic.

Differential Geometry · Mathematics 2018-12-27 Libing Huang , Zhongmin Shen

Let X be an orthogonal Grassmannian parametrizing isotropic subspaces in an even dimensional vector space equipped with a nondegenerate symmetric form. We prove a Giambelli formula which expresses an arbitrary Schubert class in the singular…

Algebraic Geometry · Mathematics 2012-04-02 Anders S. Buch , Andrew Kresch , Harry Tamvakis

The quantum cohomology algebra of the (full) flag manifold is a fundamental example in quantum cohomology theory, with connections to combinatorics, algebraic geometry, and integrable systems. Using a differential geometric approach, we…

Differential Geometry · Mathematics 2007-05-23 A. Amarzaya , M. A. Guest