Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Compatible Discrete Series   Several very interesting results connecting the theory of abelian ideals of
Borel subalgebras, some ideas of D. Peterson relating the previous theory to
the combinatorics of affine Weyl groups, and the theory of discrete series are
stated in a recent paper (\cite{Ko2}) by B. Kostant. In this paper we provide
proofs for most of Kostant's results extending them to $ad$-nilpotent ideals
and develop one direction of Kostant's investigation, the compatible discrete
series.

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The categories of this paper are: physics
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The categories of this paper are: plasm-ph
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The categories of this paper are: nucl-ex
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The categories of this paper are: econ
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The categories of this paper are: acc-phys
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The categories of this paper are: astro-ph
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The categories of this paper are: eess
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The categories of this paper are: hep-lat
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The categories of this paper are: quant-ph
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The categories of this paper are: dg-ga
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The categories of this paper are: hep-th
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The categories of this paper are: comp-gas
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The categories of this paper are: adap-org
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The categories of this paper are: hep-ex
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The categories of this paper are: cond-mat
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The categories of this paper are: patt-sol