arXiv subjects

Geetha Thangavelu

Publications and source records attributed to Geetha Thangavelu.

6 recordsLinked to original sources

arXiv2025

Construction of Young modules and filtration multiplicities for Brauer algebras of type $C$

In this paper, we construct the permutation modules and Young modules for Brauer algebras of type $C$ by extending the representation theory of the group algebra of hyperoctahedral groups. Additionally, we develop a stratifying system for Brauer algebras of type $C$, thereby extending the work of Hemmer-Nakano in \cite{HN} on Hecke algebras. This framework allows us to determine when the multiplicities of cell modules in any filtration are well-defined. As a result, we prove that if the characteristic of the field is neither $2$ nor $3$, then every permutation module of the Brauer algebra of type $C$ decomposes into a direct sum of indecomposable Young modules. We also establish certain cohomological criteria for the group algebra of the hyperoctahedral groups, which are necessary to prove the results for the Brauer algebras of type $C$.

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arXiv2025

Hook fusion procedure for direct product of symmetric groups

In this work, we derive a new expression for the diagonal matrix elements of irreducible representations of the direct product group $S_r\times S_s$ using Grime's hook fusion procedure for symmetric groups, which simplifies the fusion procedure by reducing the number of auxiliary parameters needed. By extending this approach to the product group setting, we provide a method for constructing a complete set of orthogonal primitive idempotents.

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arXiv2025

Hook fusion procedure for hyper-octahedral groups

We derive a new expression for the diagonal matrix elements of irreducible representations of the hyperoctahedral group. This expression is obtained using Grime's hook fusion procedure for symmetric groups, which minimizes the number of auxiliary parameters required in the fusion process.

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arXiv2025

Permutation modules of the walled Brauer algebras

In this article, we study the permutation modules and Young modules of the group algebras of the direct product of symmetric groups $K\mathfrak{S}_{a,b}$, and the walled Brauer algebras $\B_{r,t}(δ)$. In the category of dual Specht-filtered modules, if the characteristic of the field is neither $2$ nor $3$, then the permutation modules are dual Specht filtered, and the Young modules are relative projective cover of the dual Specht modules. We prove that the restriction of the cell modules of $\B_{r,t}(δ)$ to the group algebras of the direct product of the symmetric groups is dual Specht filtered, and the Young modules act as the relative projective cover of the cell modules of $\B_{r,t}(δ)$. Finally, we prove that if $\mathrm{char}~K \neq 2,3$, then the permutation module of $\B_{r,t}(δ)$ can be written as a direct sum of indecomposable Young modules.

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arXiv2025

Comparing cohomology via exact split pairs in diagram algebras

In this article, we compare the cohomology between the categories of modules of the diagram algebras and the categories of modules of its input algebras. Our main result establishes a sufficient condition for exact split pairs between these two categories, analogous to a work by Diracca and Koenig in [7]. To be precise, we prove the existence of the exact split pairs in $A$-Brauer algebras, cyclotomic Brauer algebras, and walled Brauer algebras with their respective input algebras.

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arXiv2024

Iwahori-Hecke algebras acting on tensor space by $q$-deformed letter permutations and $q$-partition algebras

Let $R$ be a commutative ring with identity and let $V$ be a free $R$-module of rank $n$ for some $n\in\mathbb{N}$. Fixing an $R$-basis $\mathcal{E}$ of $V$, the symmetric group $\mathfrak{S}_n$ acts on $V$ by permuting $\mathcal{E}$ and hence on tensor space $V^{\otimes r}$ for $r\in\mathbb{N}$ via the usual tensor product action turning $V$ and $V^{\otimes r}$ into $R\mathfrak{S}_n$-modules. For units $q$ in $R$ we construct an action of the corresponding Iwahori-Hecke algebra $\mathcal{H}_{R,q}(\mathfrak{S}_n)$ which specializes to the action of $R\mathfrak{S}_n$, if $q$ is taken to $1$. The centralizing algebra of this action is called the $q$-partition algebra $\mathcal{P}_{R,q}(n,r)$. Let $R$ be a field of characteristic not dividing $q$. We prove, that $\mathcal{P}_{R,q}(n,r)$ is isomorphic to the $q$-partition algebra defined by Halverson and Thiem by different means a few years ago.

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