TENSOR-CLOSED OBJECTS IN THE BGG CATEGORY OF A QUANTIZED SEMISIMPLE LIE ALGEBRA

We consider the BGG category $\O$ of a quantized universal enveloping algebra $U_q(\mathfrak{g})$. We call a module $M\in \O$ tensor-closed if $M\otimes N\in\O$ for any $N\in \O$. In this paper we prove that $M\in \O$ is tensor-closed if and only if $M$ is finite dimensional. The method used in this paper applies to the unquantized case as well.

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  • H. H. Andersen and V. Mazorchuk, Category $\mathscr{O}$ for quantum groups, J. Eur. Math. Soc., 17(2) (2015), 405-431.
  • J. E. Humphreys, Introduction to Lie Algebras and Representation Theory, Second printing, revised, Graduate Texts in Mathematics, 9, Springer-Verlag, New York-Berlin, 1978.
  • J. E. Humphreys, Representations of Semisimple Lie Algebras in the BGG Category $\mathscr{O}$, Graduate Studies in Mathematics, 94, American Mathematical Society, Providence, RI, 2008.
  • J. E. Humphreys, Tensor-closed objects of the BGG category $\mathscr{O}$, (2015), Preprint available on the author's website: http://people.math.umass.edu / jeh/pub/ tensor.pdf.
  • A. Joseph, Quantum Groups and Their Primitive Ideals, Ergebnisse der Mathematik und ihrer Grenzgebiete, (3) 29, Springer-Verlag, Berlin, 1995.
  • V. A. Lunts and A. L. Rosenberg, Localization for quantum groups, Selecta Math. (N.S.), 5(1) (1999), 123-159.
  • C. Voigt and R. Yuncken, Complex semisimple quantum groups and representation theory, (2017), arXiv:1705.05661.
  • Z. Wei, Tensor products of infinite dimensional modules in the BGG category of a quantized simple Lie algebra of type ADE, (2019), Preprint available on the author's website: https://drive.google.com/file/d/1ZogGH4Rfenq7AXTvxOdsoqGbSHCbfrjr/view.
  • Z. Wei, Tensor products of infinite dimensional modules in the BGG category of a quantized simple Lie algebra of type ADE, (2019), Preprint available on the author's website: https://drive.google.com/file/d/1ZogGH4Rfenq7AXTvxOdsoqGbSHCbfrjr/view.