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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 present a generalization of multiple orthogonal polynomials of type I and type II, which we call multiple orthogonal polynomials of mixed type. Some basic properties are formulated, and a Riemann-Hilbert problem for the multiple…

Classical Analysis and ODEs · Mathematics 2010-07-30 E. Daems , A. B. J. Kuijlaars

Given a singular Schubert variety Z in a compact Hermitian symmetric space it is a longstanding question to determine when Z is homologous to a smooth variety Y. We identify those Schubert varieties for which there exist first-order…

Differential Geometry · Mathematics 2011-02-10 C. Robles , D. The

For the toric variety X associated to the Bruhat poset of Schubert varieties in the Grassmannian, we describe the singular locus in terms of the faces of the associated polyhedral cone. We also determine the tangent cones at the maximal…

Algebraic Geometry · Mathematics 2007-11-09 Justin A. Brown , V. Lakshmibai

We establish the formula for multiplication by the class of a special Schubert variety in the integral cohomology ring of the flag manifold. This formula also describes the multiplication of a Schubert polynomial by either an elementary…

alg-geom · Mathematics 2008-02-03 Frank Sottile

We study the multiplicity number of the characteristic cycle of the intersection complex of the matroid Schubert variety. It is shown to be a combinatorial invariant, and it can be computed by explicit formulas. We also conjecture that the…

Algebraic Geometry · Mathematics 2025-01-14 Yiyu Wang

The parabolic Kazhdan-Lusztig polynomials for Grassmannians can be computed by counting Dyck partitions. We "lift" this combinatorial formula to the corresponding category of singular Soergel bimodules to obtain bases of the Hom spaces…

Representation Theory · Mathematics 2021-09-29 Leonardo Patimo

We give a combinatorial rule for computing intersection numbers on a flag manifold which come from products of Schubert classes pulled back from Grassmannian projections. This rule generalizes the known rule for Grassmannians.

Combinatorics · Mathematics 2008-05-03 Kevin Purbhoo , Frank Sottile

The Richardson variety $X_w^v$ is defined to be the intersection of the Schubert variety $X_w$ and the opposite Schubert variety $X^v$. For $X_w^v$ in the Grassmannian, we obtain a standard monomial basis for the homogeneous coordinate ring…

Algebraic Geometry · Mathematics 2007-05-23 Victor Kreiman , V. Lakshmibai

A symmetric characteristic singular integral equation with two fixed singularities at the endpoints in the class of functions bounded at the ends is analyzed. It reduces to a vector Hilbert problem for a half-disc and then to a vector…

Complex Variables · Mathematics 2015-10-06 Y. A. Antipov

We first prove an identity involving symmetric polynomials. This identity leads us into exploring the geometry of Lagrangian Grassmannians. As an insight applications, we obtain a formula for the integral over the Lagrangian Grassmannian of…

Algebraic Geometry · Mathematics 2020-05-05 Dang Tuan Hiep

Matroid varieties are the closures in the Grassmannian of sets of points defined by specifying which Pl\"ucker coordinates vanish and which don't --- the set of nonvanishing Pl\"ucker coordinates forms a well-studied object called a…

Algebraic Geometry · Mathematics 2015-08-11 Nicolas Ford

In this paper we investigate some algebraic and geometric consequences which arise from an extremal bound on the Hilbert function of the general hyperplane section of a variety (Green's Hyperplane Restriction Theorem). These geometric…

Commutative Algebra · Mathematics 2008-09-22 Jeaman Ahn , Anthony V. Geramita , Yong Su Shin

We prove that Schubert varieties in potentially different Grassmannians are isomorphic as varieties if and only if their corresponding Young diagrams are identical up to a transposition. We also discuss a generalization of this result to…

Algebraic Geometry · Mathematics 2023-09-13 Mihail Tarigradschi , Weihong Xu

In this paper, we give new explicit representations of the Hilbert scheme of $\mu$ points in $\PP^{r}$ as a projective subvariety of a Grassmanniann variety. This new explicit description of the Hilbert scheme is simpler than the previous…

Symbolic Computation · Computer Science 2010-08-04 Mariemi Alonso , Jérome Brachat , Bernard Mourrain

We express a Schubert expansion of the Chern-Mather class for Schubert varieties in the even orthogonal Grassmannian via integrals involving Pfaffians and pushforward of the small resolutions in the sense of Intersection Cohomology (IH)…

Algebraic Geometry · Mathematics 2023-03-31 Minyoung Jeon

We study subsets of Grassmann varieties G(l,m) over a field F, such that these subsets are unions of Schubert cycles, with respect to a fixed flag. We study the linear spans of, and in case of positive characteristic, the number of points…

Algebraic Geometry · Mathematics 2007-05-23 Johan P. Hansen , Trygve Johnsen , Kristian Ranestad

We give an elementary proof of the Pieri-type formula in the cohomology of a Grassmannian of maximal isotropic subspaces of an odd orthogonal or symplectic vector space. This proof proceeds by explicitly computing a triple intersection of…

alg-geom · Mathematics 2008-02-03 Frank Sottile

For the bi-orthogonal polynomials with the third degree polynomial potential functions, the 3 x 3 matrix Riemann-Hilbert problem is explicitly constructed. The developed approach admits an extension to the bi-orthogonal polynomials with…

Exactly Solvable and Integrable Systems · Physics 2008-11-26 Andrei A. Kapaev

By applying a Gr\"{o}bner-Shirshov basis of the symmetric group $S_{n}$, we give two formulas for Schubert polynomials, either of which involves only nonnegative monomials. We also prove some combinatorial properties of Schubert…

Rings and Algebras · Mathematics 2017-09-15 Zerui Zhang , Yuqun Chen