{ "id": "2007.09725", "version": "v1", "published": "2020-07-19T17:27:28.000Z", "updated": "2020-07-19T17:27:28.000Z", "title": "Outer space for RAAGs", "authors": [ "Corey Bregman", "Ruth Charney", "Karen Vogtmann" ], "comment": "53 pages, 16 figures", "categories": [ "math.GR", "math.GT" ], "abstract": "For any right-angled Artin group $A_{\\Gamma}$ we construct a finite-dimensional space $\\mathcal{O}_{\\Gamma}$ on which the group $\\text{Out}(A_{\\Gamma})$ of outer automorphisms of $A_{\\Gamma}$ acts properly. We prove that $\\mathcal{O}_{\\Gamma}$ is contractible, so that the quotient is a rational classifying space for $\\text{Out}(A_{\\Gamma})$. The space $\\mathcal{O}_{\\Gamma}$ blends features of the symmetric space of lattices in $\\mathbb{R}^n$ with those of Outer space for the free group $F_n$. Points in $\\mathcal{O}_{\\Gamma}$ are locally CAT(0) metric spaces that are homeomorphic (but not isometric) to certain locally CAT(0) cube complexes, marked by an isomorphism of their fundamental group with $A_{\\Gamma}$.", "revisions": [ { "version": "v1", "updated": "2020-07-19T17:27:28.000Z" } ], "analyses": { "subjects": [ "20F65", "20F28", "20F36" ], "keywords": [ "outer space", "locally cat", "metric spaces", "fundamental group", "cube complexes" ], "note": { "typesetting": "TeX", "pages": 53, "language": "en", "license": "arXiv", "status": "editable" } } }