ħ-Deformed Schubert Calculus in Equivariant Cohomology, K-Theory, and Elliptic Cohomology

2021 ◽  
pp. 73-96
Author(s):  
Richárd Rimányi
Keyword(s):  
Equivariant Cohomology ◽  
Schubert Calculus ◽  
Elliptic Cohomology ◽  
K Theory

scholarly journals On Schubert calculus in elliptic cohomology

2015 ◽  
Vol DMTCS Proceedings, 27th... (Proceedings) ◽  
Author(s):  
Cristian Lenart ◽  
Kirill Zainoulline
Keyword(s):  
Formal Group ◽  
Schubert Calculus ◽  
Elliptic Cohomology ◽  
Reduced Word ◽  
Combinatorial Result ◽  
International Audience ◽  
Schubert Classes ◽  
K Theory ◽  
Nous Utilisons ◽  
Group Law

International audience An important combinatorial result in equivariant cohomology and $K$-theory Schubert calculus is represented by the formulas of Billey and Graham-Willems for the localization of Schubert classes at torus fixed points. These formulas work uniformly in all Lie types, and are based on the concept of a root polynomial. We define formal root polynomials associated with an arbitrary formal group law (and thus a generalized cohomology theory). We usethese polynomials to simplify the approach of Billey and Graham-Willems, as well as to generalize it to connective $K$-theory and elliptic cohomology. Another result is concerned with defining a Schubert basis in elliptic cohomology (i.e., classes independent of a reduced word), using the Kazhdan-Lusztig basis of the corresponding Hecke algebra. Un résultat combinatoire important dans le calcul de Schubert pour la cohomologie et la $K$-théorie équivariante est représenté par les formules de Billey et Graham-Willems pour la localisation des classes de Schubert aux points fixes du tore. Ces formules sont uniformes pour tous les types de Lie, et sont basés sur le concept d’un polynôme de racines. Nous définissons les polynômes formels de racines associées à une loi arbitraire de groupe formel (et donc à une théorie de cohomologie généralisée). Nous utilisons ces polynômes pour simplifier les preuves de Billey et Graham-Willems, et aussi pour généraliser leurs résultats à la $K$-théorie connective et la cohomologie elliptique. Un autre résultat concerne la définition d’une base de Schubert dans cohomologie elliptique (c’est à dire, des classes indépendantes d’un mot réduit), en utilisant la base de Kazhdan-Lusztig de l’algèbre de Hecke correspondant.

scholarly journals The elliptic Weyl character formula

2014 ◽  
Vol 150 (7) ◽  
pp. 1196-1234 ◽  
Author(s):  
Nora Ganter
Keyword(s):  
Line Bundle ◽  
Lie Groups ◽  
Theoretical Framework ◽  
Flag Variety ◽  
Schubert Calculus ◽  
Character Formula ◽  
Elliptic Cohomology ◽  
Image Position ◽  
Weyl Character Formula

AbstractWe calculate equivariant elliptic cohomology of the partial flag variety$\def \xmlpi #1{}\def \mathsfbi #1{\boldsymbol {\mathsf {#1}}}\let \le =\leqslant \let \leq =\leqslant \let \ge =\geqslant \let \geq =\geqslant \def \Pr {\mathit {Pr}}\def \Fr {\mathit {Fr}}\def \Rey {\mathit {Re}}G/H$, where$H\subseteq G$are compact connected Lie groups of equal rank. We identify the${\rm RO}(G)$-graded coefficients${\mathcal{E}} ll_G^*$as powers of Looijenga’s line bundle and prove that transfer along the map$$\begin{equation*} \pi \,{:}\,G/H\longrightarrow {\rm pt} \end{equation*}$$is calculated by the Weyl–Kac character formula. Treating ordinary cohomology,$K$-theory and elliptic cohomology in parallel, this paper organizes the theoretical framework for the elliptic Schubert calculus of [N. Ganter and A. Ram,Elliptic Schubert calculus, in preparation].

scholarly journals An algebraic model for rational naïve-commutative ring SO(2)-spectra and equivariant elliptic cohomology

2020 ◽  
Author(s):  
David Barnes ◽  
J. P. C. Greenlees ◽  
Magdalena Kędziorek
Keyword(s):  
Elliptic Curve ◽  
Commutative Ring ◽  
Equivariant Cohomology ◽  
Algebraic Model ◽  
Homotopy Groups ◽  
Torsion Point ◽  
Ring Spectrum ◽  
Elliptic Cohomology ◽  
Commutative Algebras ◽  
Category Of Modules

Abstract Equipping a non-equivariant topological $$\text {E}_\infty $$ E ∞ -operad with the trivial G-action gives an operad in G-spaces. For a G-spectrum, being an algebra over this operad does not provide any multiplicative norm maps on homotopy groups. Algebras over this operad are called naïve-commutative ring G-spectra. In this paper we take $$G=SO(2)$$ G = S O ( 2 ) and we show that commutative algebras in the algebraic model for rational SO(2)-spectra model rational naïve-commutative ring SO(2)-spectra. In particular, this applies to show that the SO(2)-equivariant cohomology associated to an elliptic curve C of Greenlees (Topology 44(6):1213–1279, 2005) is represented by an $$\text {E}_\infty $$ E ∞ -ring spectrum. Moreover, the category of modules over that $$\text {E}_\infty $$ E ∞ -ring spectrum is equivalent to the derived category of sheaves over the elliptic curve C with the Zariski torsion point topology.

scholarly journals Equivariant K-theory and equivariant cohomology

2003 ◽  
Vol 243 (3) ◽  
pp. 423-448 ◽  
Author(s):  
Ioanid Rosu
Keyword(s):  
Equivariant Cohomology ◽  
K Theory

scholarly journals Eigenvalues of Hermitian matrices and equivariant cohomology of Grassmannians

2013 ◽  
Vol 149 (9) ◽  
pp. 1569-1582 ◽  
Author(s):  
David Anderson ◽  
Edward Richmond ◽  
Alexander Yong
Keyword(s):  
Eigenvalue Problem ◽  
Recent Work ◽  
Equivariant Cohomology ◽  
Eigenvalue Problems ◽  
Schubert Calculus ◽  
Hermitian Matrices ◽  
Common Features ◽  
Saturation Theorem ◽  
The Common

AbstractThe saturation theorem of Knutson and Tao concerns the nonvanishing of Littlewood–Richardson coefficients. In combination with work of Klyachko, it implies Horn’s conjecture about eigenvalues of sums of Hermitian matrices. This eigenvalue problem has a generalization to majorized sums of Hermitian matrices, due to S. Friedland. We further illustrate the common features between these two eigenvalue problems and their connection to Schubert calculus of Grassmannians. Our main result gives a Schubert calculus interpretation of Friedland’s problem, via equivariant cohomology of Grassmannians. In particular, we prove a saturation theorem for this setting. Our arguments employ the aforementioned work together with recent work of H. Thomas and A. Yong.

scholarly journals EQUIVARIANT -THEORY OF GRASSMANNIANS

2017 ◽  
Vol 5 ◽  
Author(s):  
OLIVER PECHENIK ◽  
ALEXANDER YONG
Keyword(s):  
Equivariant Cohomology ◽  
Homogeneous Spaces ◽  
Acta Math ◽  
Schubert Calculus ◽  
Duke Math ◽  
Jeu De Taquin ◽  
Lecture Notes ◽  
Equivariant Theory

We address a unification of the Schubert calculus problems solved by Buch [A Littlewood–Richardson rule for the $K$-theory of Grassmannians, Acta Math. 189 (2002), 37–78] and Knutson and Tao [Puzzles and (equivariant) cohomology of Grassmannians, Duke Math. J.119(2) (2003), 221–260]. That is, we prove a combinatorial rule for the structure coefficients in the torus-equivariant $K$-theory of Grassmannians with respect to the basis of Schubert structure sheaves. This rule is positive in the sense of Anderson et al. [Positivity and Kleiman transversality in equivariant $K$-theory of homogeneous spaces, J. Eur. Math. Soc.13 (2011), 57–84] and in a stronger form. Our work is based on the combinatorics of genomic tableaux and a generalization of Schützenberger’s [Combinatoire et représentation du groupe symétrique, in Actes Table Ronde CNRS, Univ. Louis-Pasteur Strasbourg, Strasbourg, 1976, Lecture Notes in Mathematics, 579 (Springer, Berlin, 1977), 59–113] jeu de taquin. Using our rule, we deduce the two other combinatorial rules for these coefficients. The first is a conjecture of Thomas and Yong [Equivariant Schubert calculus and jeu de taquin, Ann. Inst. Fourier (Grenoble) (2013), to appear]. The second (found in a sequel to this paper) is a puzzle rule, resolving a conjecture of Knutson and Vakil from 2005.

scholarly journals Genomic Tableaux and Combinatorial $K$-Theory

2015 ◽  
Vol DMTCS Proceedings, 27th... (Proceedings) ◽  
Author(s):  
Oliver Pechenik ◽  
Alexander Yong
Keyword(s):  
Schubert Calculus ◽  
Nous Obtenons ◽  
International Audience ◽  
Structure Constants ◽  
K Theory ◽  
Orthogonal Grassmannians

International audience We introduce genomic tableaux, with applications to Schubert calculus. We report a combinatorial rule for structure coefficients in the torus-equivariant $K$-theory of Grassmannians for the basis of Schubert structure sheaves. This rule is positive in the sense of [Anderson-Griffeth-Miller ’11]. We thereby deduce an earlier conjecture of [Thomas-Yong ’13] for the coefficients. Moreover, our rule specializes to give a new Schubert calculus rule in the (non-equivariant) $K$-theory of Grassmannians. From this perspective, we also obtain a new rule for $K$-theoretic Schubert structure constants of maximal orthogonal Grassmannians, and give conjectural bounds on such constants for Lagrangian Grassmannians. Nous introduisons la notion de tableau génomique, pour l’appliquer au calcul de Schubert. Nous énonçons une règle combinatoire pour les coefficients de structure de la $K$-théorie tore-équivariante des grassmanniennes, dans la base définie par les classes des faisceaux structuraux des variétés de Schubert. Cette règle est positive au sens de [Anderson-Griffeth-Miller ’11]. Nous en déduisons une conjecture de [Thomas-Yong ’13]. De plus, notre règle se spécialise en une règle nouvelle pour le calcul de Schubert dans la $K$-théorie (non équivariante) des grassmanniennes. Nous obtenons également une nouvelle règle pour les coefficients de structure de la $K$-théorie des grassmanniennes orthogonales maximales dans la base de Schubert, et nous conjecturons certaines bornes pour ces coefficients dans le cas des grassmanniennes lagrangiennes.

scholarly journals DHD-puzzles

2020 ◽  
Vol DMTCS Proceedings, 28th... ◽  
Author(s):  
Sabine Beil
Keyword(s):  
Schubert Calculus ◽  
The Other ◽  
Fixed Boundary ◽  
Puzzle Piece ◽  
Other Hand ◽  
International Audience ◽  
K Theory ◽  
The One

International audience In this work triangular puzzles that are composed of unit triangles with labelled edges are considered. To be more precise, the labelled unit triangles that we allow are on the one hand the puzzle pieces that compute Schubert calculus and on the other hand the flipped K-theory puzzle piece. The motivation for studying such puzzles comes from the fact that they correspond to a class of oriented triangular fully packed loop configurations. The main result that is presented is an expression for the number of these puzzles with a fixed boundary in terms of Littlewood- Richardson coefficients.

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