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Thomas Pietraho

Publications and source records attributed to Thomas Pietraho.

11 recordsLinked to original sources
arXiv2026

On the classification of primitive ideals for complex classical Lie algebras, IV

This paper is the fourth and last in the series "On the classification of primitive ideals for complex classical Lie algebras", extending earlier results in other classical types to type D. The generalized tau-invariant used in earlier work must now be defined in a different way, using a family of operators attached to a quadruple of simple roots spanning a subsystem of type D_4. each taking one or two values. Using these operators we show that primitive ideals of trivial infinitesimal character are characterized by their generalized tau-invariants and are parametrized by standard domino tableaux of the appropriate special shape.

math.RT↗
arXiv2013

Sign under the domino Robinson-Schensted maps

We generalize a formula obtained independently by A. Reifegerste and J. Sjöstrand for the sign of a permutation under the classical Robinson-Schensted map to a family of domino Robinson-Schensted algorithms.

math.CO↗
arXiv2009

Orbital Varieties and Unipotent Representations

Using the notion of a Lagrangian covering, W. Graham and D. Vogan proposed a method of constructing representations from the coadjoint orbits for a complex semisimple Lie group $G$. When the coadjoint orbit $\calO$ is nilpotent, a representation of $G$ is attached to each orbital variety of $\calO$ in this way. In the setting of classical groups, we show that whenever it is possible to carry out the Graham-Vogan construction for an orbital variety of a spherical $\mathcal{O}$, its infinitesimal character lies in a set of characters attached to $\mathcal{O}$ by W. M. McGovern. Furthermore, we show that it is possible to carry out the Graham-Vogan construction for a sufficient number of orbital varieties to account for all the infinitesimal characters in this set.

math.RT↗
arXiv2009

Module structure of cells in unequal parameter Hecke algebras

A conjecture of C. Bonnafé, M. Geck, L. Iancu, and T. Lam parameterizes Kazhdan-Lusztig left cells for unequal parameter Hecke algebras in type $B_n$ by families of standard domino tableaux of arbitrary rank. Relying on a family of properties outlined by G. Lusztig and the recent work of C. Bonnafé, we verify the conjecture and describe the structure of each cell as a module for the underlying Weyl group.

math.RT↗
arXiv2008

Cells and Constructible Representations in type B

We examine the partition of a finite Coxeter group of type $B$ into cells determined by a weight function $L$. The main objective of these notes is to reconcile Lusztig's description of constructible representations in this setting with conjectured combinatorial descriptions of cells.

math.RT↗
arXiv2008

Knuth Relations for the Hyperoctahedral Groups

C. Bonnaf{é}, M. Geck, L. Iancu, and T. Lam have conjectured a description of one-sided cells in unequal parameter Hecke algebras of type $B$ which is based on domino tableaux of arbitrary rank. In the integer case, this generalizes the work of D. Garfinkle whose methods we adapt to construct a family of operators which generate the conjectured combinatorial description.

math.RT↗
arXiv2007

A Relation for Domino Robinson-Schensted Algorithms

We describe a relationship between Robinson-Schensted algorithms defined for standard domino tableaux of unequal rank. The principal idea is the moving-through operation defined on standard domino tableaux by D. Garfinkle. When restricted to involutions, this answers a question posed by M.A.A. van Leeuwen.

math.CO↗
arXiv2007

Equivalence Classes in the Weyl groups of type $B_n$

We consider two families of equivalence classes in the Weyl groups of type $B_n$ which are suggested by the study of left cells in unequal parameter Iwahori-Hecke algebras. Both families are indexed by a non-negative integer $r$. For $r=0$, the classes in the first family coincide with left cells corresponding to the equal parameter Iwahori-Hecke algebra. When $r$ is sufficiently large, the equivalence classes in the second family agree with left cells corresponding to a special class of choices of unequal parameters. Our main result shows that the two families of equivalence classes coincide, suggesting the structure of left cells for remaining choices of the Iwahori-Hecke algebra parameters.

math.CO↗
arXiv2002

Components of the Springer Fiber and Domino Tableaux

Consider a complex classical semi-simple Lie group along with the set of its nilpotent coadjoint orbits. When the group is of type A, the set of orbital varieties contained in a given nilpotent orbit is described a set of standard Young tableaux. We parameterize both, the orbital varieties and the irreducible components of unipotent varieties in the other classical groups by sets of standard domino tableaux. The main tools are Spaltenstein's results on signed domino tableaux together with Garfinkle's operations on standard domino tableaux.

math.RT↗