2014/05/25 by Guilnard Sadaka, Sadaka, Guilnard
Mathematics · #17B20 #17B35 #Advanced Algebra and Geometry #Advanced Topics in Algebra #Algebraic structures and combinatorial models #FOS: Mathematics #Representation Theory (math.RT) #math.RT #msc:17B20 #msc:17B35
paper · pdf · doi:10.48550/arxiv.1405.6390
49 pages in French. This paper is mostly extracted from my PhD thesis. It strictly contains the results of ArXiv:1206.1436 with further generalizations
arxiv created 2014/05/25 · openalex publication_date 2014/05/25 · arxiv updated 2014/05/27 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
Let g be a complex simple Lie algebra and e a nilpotent element of g. We are interested in the isomorphism question (raised by Premet) between the finite W-algebras constructed from some nilpotent subalgebras of g called e-admissible. We introduce the concept of e-admissible pairs and e-admissible gradings. We show that the W-algebra associated to an e-admissible pair admits similar properties to the ones introduced by Gan and Ginzburg. Moreover, we define an equivalence relation on the set of admissible pairs and we show that if two admissible pairs are equivalent, it follows that the associated W-algebras are isomorphic. By introducing the notion of connectivity of admissible gradings, we reduce the isomorphism question to the study of the equivalence of admissible pairs for a fixed admissible grading. This allows us to prove that admissible pairs relative to b-optimal gradings are equivalent, hence the corresponding W algebras are isomorphic. We recover as a special case a result of Brundan and Goodwin. In the final part, we use our results to find a complete answer to the isomorphism question in some particular cases.