arXiv subjects
Publications and source records attributed to G. Lusztig.
Let W be a Weyl group and let w be a Coxeter elememt of minimal length of W. In the early 1970's I.G.Macdonald stated that the trace of w on an irreducible representation of W is 0,1 or -1. In this paper we give a proof of this statement and of an Iwahori-Hecke algebra version of it.
In a 2015 paper we have defined a map from the set of conjugacy classes in a Weyl group W to the set of irreducible representations of W (its image parametrizes the strata of a reductive group with Weyl group W). In this paper we provide evidence that this map makes sense even when W is replaced by a noncrystallographic Coxeter group.
Let G be a connected reductive group over the complex numbers with a fixed pinning. We define and study the totally positive part of the set of maximal tori of G.
We show how to attach to any stratum of a reductive group a (small) finite group. We also show that in the simply laced case the set of strata is in bijection with a subset of the set of almost special representations of the Weyl group. (This is the same as version 1 except that the abstract has been corrected.)
We prove a montonicity property of the new basis of C[(Z/2)^D]. We also study the matrix coefficients of the Fourier transform with respect to the new basis and formulate a conjecture for them.
Let $c$ be the family of irreducible representations of a Weyl group $W$ corresponding to a two-sided cell of $W$. We define a subset $A_c$ of $c$ which contains the special representation of $W$ in $c$ and is in canonical bijection with the set of constructible representations of $W$ attached to $c$.
We give an explanation of the bijection between geometric and arithmetic diagrams attached to supercuspidal unipotent representations of a simple p-adic group which is based purely on algebra. The second version contains much additional material compared to the first version.
We study the intersection of the totally positive part of a split semisimple group over the real numbers with a totally positive parabolic subgroup.
We give a parametrization of the canonical basis of the modified quantum group corresponding to a root datum in terms of the flag manifold over the semifield Z associated to the reductive group corresponding to the dual root datum. Some minor errors corrected.
Let H be a connected reductive group over an algebraically closed field. We define a surjective map from the set CS(H) of unipotent character sheaves on H (up to isomorphism) to the set of strata of H. To do this we use the generalized Springer correspondence. We also give a new parametrization of CS(H) in terms of data coming from bad characteristic. Some minor errors corrected.
We define precuspidal families in proper parabolic subgroups of a Weyl group and we show how to use them to index the irreducible representations of that Weyl group in terms of certain pairs of finite groups. Some additional material is added.
In previous papers the author introduced a new basis of the Grpthendieck group of unipotent representations of a finite Chevalley group. In type D the definition of this basis was stated without proof. In this paper we provide the missing proof.
For a symplectic vector space V over Z/2 with a given circular basis we give a non-inductive definition of a family of isotropic subspaces of V with remarkable properties.
We study the local and global intersection cohomology of the intersection of two Schubert varieties in a flag manifold. In this version some new references are added.
Let D be a connected component of a reductive group over an algebraically closed field. We define a surjective map from the unipotent character sheaves on D to the set of strata of D, extending an earlier result which applied to connected reductive groups.
We define (in two, equivalent ways) the notion of a rigid stratum of a reductive group. This generalizes the notion of rigid unipotent class.
A flag manifold over a semifield K can be partitioned into "half i-circles" which are orbits of a K-action on that flag manifold. Here i is fixed and it corresponds to a simple reflection in the Weyl group. We prove (for certain K) a connectedness property of the flag manifold: any two points of it can be joined by a finite sequence of half i-circles for various i.
We define a map from the unipotent representations of a split semisimple group over a finite field to (essentially) the set of pairs of left cells representations of the Weyl group in the same two-sided cell. We use this map to parametrize the unipotent representations.