View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by Elsevier - Publisher Connector Advances in Mathematics 196 (2005) 193–256 www.elsevier.com/locate/aim Representation type of the blocks of category Os Brian D. Boe, Daniel K. Nakano∗,1 Department of Mathematics, University of Georgia, Athens, GA 30602, USA Received 17 May2004; accepted 6 September 2004 Communicated byD.J. Benson Available online 5 November 2004 Abstract In this paper the authors investigate the representation type of the blocks of the relative (parabolic) category OS for complex semisimple Lie algebras. A complete classification of the blocks corresponding to regular weights is given. The main results of the paper provide a classification of the blocks in the “mixed” case when the simple roots corresponding to the singular set and S do not meet. © 2004 Elsevier Inc. All rights reserved. MSC: 17B10 Keywords: Category O; Representation type; Verma modules 1. Introduction 1.1. The studyof indecomposable modules is a central theme in the representation theoryof finite-dimensional algebras. One can place a finite-dimensional algebra in one of three classes depending on the indecomposable modules the algebra admits. A finite-dimensional algebra has finite representation type if the algebra has finitely manyindecomposable modules up to isomorphism. If the algebra does not have finite ∗ Corresponding author. E-mail addresses:
[email protected] (B.D. Boe),
[email protected] (D.K. Nakano). 1 Research partiallysupported byNSF Grant DMS-0102225. 0001-8708/$ - see front matter © 2004 Elsevier Inc. All rights reserved. doi:10.1016/j.aim.2004.09.001 194 B.D.