Kyoto Journal of Mathematics

A Fock space model for decomposition numbers for quantum groups at roots of unity

Martina Lanini, Arun Ram, and Paul Sobaje

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In this paper we construct an abstract Fock space for general Lie types that serves as a generalization of the infinite wedge q-Fock space familiar in type A. Specifically, for each positive integer , we define a Z[q,q1]-module F with bar involution by specifying generators and straightening relations adapted from those appearing in the Kashiwara–Miwa–Stern formulation of the q-Fock space. By relating F to the corresponding affine Hecke algebra, we show that the abstract Fock space has standard and canonical bases for which the transition matrix produces parabolic affine Kazhdan–Lusztig polynomials. This property and the convenient combinatorial labeling of bases of F by dominant integral weights makes F a useful combinatorial tool for determining decomposition numbers of Weyl modules for quantum groups at roots of unity.

Article information

Kyoto J. Math., Volume 59, Number 4 (2019), 955-991.

Received: 30 December 2016
Revised: 21 February 2017
Accepted: 22 June 2017
First available in Project Euclid: 22 October 2019

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Mathematical Reviews number (MathSciNet)

Zentralblatt MATH identifier

Primary: 17B37: Quantum groups (quantized enveloping algebras) and related deformations [See also 16T20, 20G42, 81R50, 82B23]
Secondary: 20C20: Modular representations and characters

quantum groups Fock space Hecke algebra multiplicity formulas


Lanini, Martina; Ram, Arun; Sobaje, Paul. A Fock space model for decomposition numbers for quantum groups at roots of unity. Kyoto J. Math. 59 (2019), no. 4, 955--991. doi:10.1215/21562261-2019-0031.

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