Generalized Bruhat decompositions and infinite lattice varieties: an introduction to Langlands duals in the theory of loop and looplike spaces -- William Haboush
If G is a reductive algebraic group over k then it is well known that the triple consisting of a Borel subgroup, a Cartan subgroup and a set of fundamental reflections constitutes a Tits system (BN pair) and that the associated double coset decomposition is the Bruhat decomposition. I will explain how the triple consisting of an Iwahori subgroup, a Cartan subgroup and another set of reflections constitutes a Tits system and how the corresponding double coset decomposition is indexed by objects which are associated to the Langlands dual. Since these double cosets detemine cellular decompositions of the loop Grassmannian, the classical Cartan-Chevalley-Demazure computation of the cohomology rings, K-theory and Chow rings of flag varieties suggests the program of Ginzburg, Drinfeld, Bezrukavnikov and others.