{ "id": "1902.04883", "version": "v1", "published": "2019-02-13T13:13:18.000Z", "updated": "2019-02-13T13:13:18.000Z", "title": "A cubical flat torus theorem and some of its applications", "authors": [ "Anthony Genevois" ], "comment": "34 pages, 10 figures. Comments are welcome!", "categories": [ "math.GR" ], "abstract": "The article is dedicated to the proof of the following cubical version of the flat torus theorem. Let $G$ be a group acting on a CAT(0) cube complex $X$ and $A \\leq G$ a normal finitely generated abelian subgroup. Then there exists a median subalgebra $Y \\subset X$ which is $G$-invariant and which decomposes as a product of median algebras $T \\times F \\times Q$ such that: (1) the action $G \\curvearrowright Y$ decomposes as a product of actions $G \\curvearrowright T,F,Q$; (2) $F$ is a \\emph{flat}; (3) $Q$ is a finite-dimensional cube; (4) $A$ acts trivially on $T$. Some applications are included. For instance, a splitting theorem is proved and we show that a polycyclic group acting properly on a CAT(0) cube complex must be virtually abelian.", "revisions": [ { "version": "v1", "updated": "2019-02-13T13:13:18.000Z" } ], "analyses": { "subjects": [ "20F65", "20F67", "20F16" ], "keywords": [ "cubical flat torus theorem", "applications", "cube complex", "normal finitely generated abelian subgroup", "median subalgebra" ], "note": { "typesetting": "TeX", "pages": 34, "language": "en", "license": "arXiv", "status": "editable" } } }