{ "id": "1905.00613", "version": "v1", "published": "2019-05-02T08:22:34.000Z", "updated": "2019-05-02T08:22:34.000Z", "title": "Combinatorics of faithfully balanced modules", "authors": [ "William Crawley-Boevey", "Biao Ma", "Baptiste Rognerud", "Julia Sauter" ], "comment": "28 pages, 5 figures", "categories": [ "math.RT", "math.CO" ], "abstract": "We study and classify faithfully balanced modules for the algebra of lower triangular $n$ by $n$ matrices. The theory extends known results about tilting modules, which are classified by binary trees, and counted with the Catalan numbers. The number of faithfully balanced modules is a $2$-factorial number. Among them are $n!$ modules with $n$ indecomposable summands, which can be classified by interleaved binary trees or by increasing binary trees.", "revisions": [ { "version": "v1", "updated": "2019-05-02T08:22:34.000Z" } ], "analyses": { "subjects": [ "16G10" ], "keywords": [ "combinatorics", "lower triangular", "interleaved binary trees", "factorial number", "increasing binary trees" ], "note": { "typesetting": "TeX", "pages": 28, "language": "en", "license": "arXiv", "status": "editable" } } }