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We derive an explicit simple formula for expectations of all Schur functions in the real Ginibre ensemble. It is a positive integer for all entries of the partition even and zero otherwise. The result can be used to determine the average of…

Mathematical Physics · Physics 2009-05-15 Hans-Juergen Sommers , Boris A Khoruzhenko

We provide a fermionic description of flagged skew Grothendieck polynomials, which can be seen as a $K$-theoretic counterpart of flagged skew Schur polynomials. Our proof relies on the Jacobi-Trudi type formula established by Matsumura.…

Combinatorics · Mathematics 2023-09-25 Shinsuke Iwao

We make a broad conjecture about the $k$-Schur positivity of Catalan functions, symmetric functions which generalize the (parabolic) Hall-Littlewood polynomials. We resolve the conjecture with positive combinatorial formulas in cases which…

Combinatorics · Mathematics 2018-11-07 Jonah Blasiak , Jennifer Morse , Anna Pun , Daniel Summers

We use dual equivalence to give a short, combinatorial proof that Stanley symmetric functions are Schur positive. We introduce weak dual equivalence, and use it to give a short, combinatorial proof that Schubert polynomials are key…

Combinatorics · Mathematics 2017-02-15 Sami Assaf

We consider a filtration of the symmetric function space given by $\Lambda^{(k)}_t$, the linear span of Hall-Littlewood polynomials indexed by partitions whose first part is not larger than $k$. We introduce symmetric functions called the…

Combinatorics · Mathematics 2007-05-23 L. Lapointe , J. Morse

We prove, combinatorially, that the product of a Schubert polynomial by a Stanley symmetric polynomial is a truncated Schubert polynomial. Using Monk's rule, we derive a nonnegative combinatorial formula for the Schubert polynomial…

Combinatorics · Mathematics 2017-02-02 Sami Assaf

The rational Cherednik algebra $\HH$ is a certain algebra of differential-reflection operators attached to a complex reflection group $W$. Each irreducible representation $S^\lambda$ of $W$ corresponds to a standard module $M(\lambda)$ for…

Representation Theory · Mathematics 2008-11-09 Stephen Griffeth

Lascoux and Sch\"utzenberger introduced Schubert and Grothendieck polynomials to study the cohomology and K-theory of the complete flag variety. We present explicit combinatorial rules for expressing Grothendieck polynomials in the basis of…

Combinatorics · Mathematics 2025-06-10 Anna Weigandt

Schur functions are a basis of the symmetric function ring that represent Schubert cohomology classes for Grassmannians. Replacing the cohomology ring with $K$-theory yields a rich combinatorial theory of inhomogeneous deformations, where…

Combinatorics · Mathematics 2023-05-19 Logan Crew , Oliver Pechenik , Sophie Spirkl

We give a combinatorial proof that the product of a Schubert polynomial by a Schur polynomial is a nonnegative sum of Schubert polynomials. Our proof uses Assaf's theory of dual equivalence to show that a quasisymmetric function of Bergeron…

Combinatorics · Mathematics 2014-05-13 Sami Assaf , Nantel Bergeron , Frank Sottile

We consider an operator of Bernstein for symmetric functions, and give an explicit formula for its action on an arbitrary Schur function. This formula is given in a remarkably simple form when written in terms of some notation based on the…

Combinatorics · Mathematics 2009-02-26 S. R. Carrell , I. P. Goulden

Given an element in a finite-dimensional real vector space, $V$, that is a nonnegative linear combination of basis vectors for some basis $B$, we compute the probability that it is furthermore a nonnegative linear combination of basis…

Combinatorics · Mathematics 2021-03-29 Rebecca Patrias , Stephanie van Willigenburg

A classical result by Schoenberg (1942) identifies all real-valued functions that preserve positive semidefiniteness (psd) when applied entrywise to matrices of arbitrary dimension. Schoenberg's work has continued to attract significant…

Combinatorics · Mathematics 2016-04-29 Alexander Belton , Dominique Guillot , Apoorva Khare , Mihai Putinar

We consider the Grothendieck polynomials appearing in the K-theory of Grassmannians, which are analogs of Schur polynomials. This paper aims to establish a version of the Murnaghan-Nakayama rule for Grothendieck polynomials of the…

Combinatorics · Mathematics 2024-05-14 Khanh Nguyen Duc , Dang Tuan Hiep , Tran Ha Son , Do Le Hai Thuy

We introduce a remarkable new family of norms on the space of $n \times n$ complex matrices. These norms arise from the combinatorial properties of symmetric functions, and their construction and validation involve probability theory,…

Combinatorics · Mathematics 2022-03-23 Konrad Aguilar , Ángel Chávez , Stephan Ramon Garcia , Jurij Volčič

Crystal skeletons were introduced by Maas-Gari\'epy in 2023 by contracting quasi-crystal components in a crystal graph. On the representation theoretic level, crystal skeletons model the expansion of Schur functions into Gessel's…

Combinatorics · Mathematics 2025-03-20 Sarah Brauner , Sylvie Corteel , Zajj Daugherty , Anne Schilling

Zernike polynomials are a basis of orthogonal polynomials on the unit disk that are a natural basis for representing smooth functions. They arise in a number of applications including optics and atmospheric sciences. In this paper, we…

Numerical Analysis · Mathematics 2018-11-08 Philip Greengard , Kirill Serkh

We prove that the symmetric function $\Delta'_{e_{k-1}}e_n$ appearing in the Delta Conjecture can be obtained from the symmetric function in the Rational Shuffle Theorem by applying a Schur skewing operator. This generalizes a formula by…

Combinatorics · Mathematics 2024-08-23 Maria Gillespie , Eugene Gorsky , Sean T. Griffin

We introduce a real-parameter refinement of the classical integer hierarchies underlying Schmidt number, block-positivity, and $k$-positivity for maps between matrix algebras. Starting from a compact family of $\alpha$-admissible unit…

Functional Analysis · Mathematics 2026-02-16 Mohsen Kian

An element of a Weyl group of classical type is skew if it is the left factor in a reduced factorization of a Grassmannian element. The skew Grothendieck polynomials are those which are indexed by skew elements of the Weyl group. We define…

Combinatorics · Mathematics 2024-01-30 Harry Tamvakis