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arXiv · 2111.11727

On first extensions in $\mathcal{S}$-subcategories of $\mathcal{O}$

Hankyung Ko·Volodymyr Mazorchuk
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Abstract

We compute the first extension group from a simple object to a proper standard object and, in some cases, the first extension group from a simple object to a standard object in the principal block of an $\mathcal{S}$-subcategory of the BGG category $\mathcal{O}$ associated to a triangular decomposition of a semi-simple finite dimensional complex Lie algebra.

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Hankyung Ko, Volodymyr Mazorchuk. 2021-11-23. On first extensions in $\mathcal{S}$-subcategories of $\mathcal{O}$. https://arxiv.org/abs/2111.11727

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