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arXiv · 2008.06679

Virtual Classes of Representation Varieties of Upper Triangular Matrices via Topological Quantum Field Theories

Márton Hablicsek·Jesse Vogel
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Abstract

In this paper, we use a geometric technique developed by Gonz\'alez-Prieto, Logares, Mu\~noz, and Newstead to study the $G$-representation variety of surface groups $\mathfrak{X}_G(\Sigma_g)$ of arbitrary genus for $G$ being the group of upper triangular matrices of fixed rank. Explicitly, we compute the virtual classes in the Grothendieck ring of varieties of the $G$-representation variety and the moduli space of $G$-representations of surface groups for $G$ being the group of complex upper triangular matrices of rank $2$, $3$, and $4$ via constructing a topological quantum field theory. Furthermore, we show that in the case of upper triangular matrices the character map from the moduli space of $G$-representations to the $G$-character variety is not an isomorphism.

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Márton Hablicsek, Jesse Vogel. 2020-08-15. Virtual Classes of Representation Varieties of Upper Triangular Matrices via Topological Quantum Field Theories. https://doi.org/10.3842/sigma.2022.095

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