Three presentations of torus equivariant cohomology of flag manifolds

Abstract

Let $G$ be a compact connected Lie group and $T$ be its maximal torus. The homogeneous space $G/T$ is called the (complete) flag manifold. One of the main goals of the {\em equivariant Schubert calculus} is to study the $T$-equivariant cohomology $H_T^{\ast }(G/T)$ with regard to the $T$-action on $G/T$ by multiplication. There are three presentations known for $H_T^{\ast }(G/T)$; (1) the free $H^{\ast }(BT)$-module generated by the Schubert varieties (2) (with the rational coefficients) the {\em double coinvariant ring} of the Weyl group (3) the {\em GKM ring} associated to the Hasse graph of the Weyl group. Each presentation has both advantages and disadvantages. In this paper, we describe how to convert an element in one presentation to another by giving an explicit algorithm, which can then be used to compute the equivariant structure constants for the product of Schubert classes. The algorithm is implemented in Maple.

fixed minor errors. added Rem 2.4

References in corpus (1)

• The graph cohomology ring of the GKM graph of a flag manifold of type $G_2$

Cited by in corpus (2)

• Equivariant cohomology rings of the real flag manifolds
• Comodule Structures, Equivariant Hopf Structures, and Generalized Schubert Polynomials