GASC Seminar

Affine Weyl groups in K-theory and representation theory


Alexander Postnikov


Northeastern University

Monday, October 6, 2003


Talk at 1:30 p.m. in 509 Lake Hall


Abstract:   We present a simple model for characters of irreducible representations of semi-simple Lie groups and, more generally, for Demazure characters. This is a combinatorial counterpart of the Littelmann path model. We give an explicit combinatorial Chevalley-type formula for equivariant K-theory of generalized flag manifolds G/B. The construction is given in terms of alcove paths, which correspond to decompositions of affine Weyl group elements, and saturated chains in the Bruhat order on the usual Weyl group. A key ingredient is a certain R-matrix that satisfies the Yang-Baxter equation.

     This is joint work with Cristian Lenart.

Here are some directions to Northeastern University. Lake Hall can be best accessed from the entrance on the corner of Greenleaf Street and Leon Street.

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