{ "id": "1112.1970", "version": "v1", "published": "2011-12-08T21:45:57.000Z", "updated": "2011-12-08T21:45:57.000Z", "title": "On Small Separations in Cayley Graphs", "authors": [ "Martha Giannoudovardi" ], "comment": "9 pages, 2 figures", "categories": [ "math.GR", "math.CO" ], "abstract": "We present two results on expansion of Cayley graphs. The first result settles a conjecture made by DeVos and Mohar. Specifically, we prove that for any positive constant $c$ there exists a finite connected subset $A$ of the Cayley graph of $\\mathbb{Z}^2$ such that $\\frac{|\\partial A|}{|A|}< \\frac{c}{depth(A)}$. This yields that there can be no universal bound for $\\frac{|\\partial A|depth(A)}{|A|}$ for subsets of either infinite or finite vertex transitive graphs. Let $X=(V,E)$ be the Cayley graph of a finitely generated infinite group and $A\\subset V$ finite such that $A\\cup\\partial A$ is connected. Our second result is that if $|A|> 16|\\partial A|^2$ then $X$ has a ring-like structure.", "revisions": [ { "version": "v1", "updated": "2011-12-08T21:45:57.000Z" } ], "analyses": { "keywords": [ "cayley graph", "small separations", "finite vertex transitive graphs", "first result settles", "universal bound" ], "note": { "typesetting": "TeX", "pages": 9, "language": "en", "license": "arXiv", "status": "editable", "adsabs": "2011arXiv1112.1970G" } } }