On the Langlands retraction
Representation Theory
2013-01-10 v1 Algebraic Geometry
Combinatorics
Abstract
Given a root system in a vector space V, Robert Langlands defined in 1973 a canonical retraction of V onto the dominant chamber. In this note we give a short review of the material on this retraction (which is well known under the name of "Langlands' geometric lemmas"). The main purpose of this review is to provide a convenient reference for e-print arXiv:1112.2402 by D.Gaitsgory and me, in which the Langlands retraction is used to define a certain coarsening of the Harder-Narasimhan-Shatz stratification of the stack of G-bundles on a smooth projective curve.
Cite
@article{arxiv.1301.1940,
title = {On the Langlands retraction},
author = {Vladimir Drinfeld},
journal= {arXiv preprint arXiv:1301.1940},
year = {2013}
}
Comments
5 pages, Latex. arXiv admin note: text overlap with arXiv:1112.2402