{ "id": "1105.1611", "version": "v5", "published": "2011-05-09T09:59:21.000Z", "updated": "2014-09-01T10:28:54.000Z", "title": "Connectivity and tree structure in finite graphs", "authors": [ "Johannes Carmesin", "Reinhard Diestel", "Fabian Hundertmark", "Maya Stein" ], "comment": "31 pages", "journal": "Combinatorica 34 (2014), pp 11-46", "doi": "10.1007/s00493-014-2898-5", "categories": [ "math.CO" ], "abstract": "Considering systems of separations in a graph that separate every pair of a given set of vertex sets that are themselves not separated by these separations, we determine conditions under which such a separation system contains a nested subsystem that still separates those sets and is invariant under the automorphisms of the graph. As an application, we show that the $k$-blocks -- the maximal vertex sets that cannot be separated by at most $k$ vertices -- of a graph $G$ live in distinct parts of a suitable tree-decomposition of $G$ of adhesion at most $k$, whose decomposition tree is invariant under the automorphisms of $G$. This extends recent work of Dunwoody and Kr\\\"on and, like theirs, generalizes a similar theorem of Tutte for $k=2$. Under mild additional assumptions, which are necessary, our decompositions can be combined into one overall tree-decomposition that distinguishes, for all $k$ simultaneously, all the $k$-blocks of a finite graph.", "revisions": [ { "version": "v4", "updated": "2013-02-04T09:50:57.000Z", "comment": "30 pages", "journal": null, "doi": null }, { "version": "v5", "updated": "2014-09-01T10:28:54.000Z" } ], "analyses": { "subjects": [ "05C40", "05C05", "05C83", "G.2.2" ], "keywords": [ "finite graph", "tree structure", "connectivity", "maximal vertex sets", "separation system contains" ], "tags": [ "journal article" ], "note": { "typesetting": "TeX", "pages": 31, "language": "en", "license": "arXiv", "status": "editable", "adsabs": "2011arXiv1105.1611C" } } }