2024/09/10 by Dylan Johnston, Johnston, Dylan, Diego Martín Duro +3
Mathematics · #20G05 #Advanced Algebra and Geometry #FOS: Mathematics #Group Theory (math.GR) #Primary 20G07 #Representation Theory (math.RT) #Secondary 20E22
paper · pdf · doi:10.48550/arxiv.2409.06375
openalex publication_date 2024/09/10 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
In this article, we classify disconnected reductive groups over an algebraically closed field with a few caveats. Internal parts of our result are both a classification of finite groups and a classification of integral representations of a fixed finite group. Modulo these classifications - which are impossible in different senses - our main result explicitly tabulates the groups with an efficient algorithm. Besides this, we obtain new results about the representation theory of disconnected reductive groups in characteristic zero. We give two descriptions of their representation rings and prove that their Knutson Index is finite.