{ "id": "0705.4153", "version": "v3", "published": "2007-05-29T07:32:27.000Z", "updated": "2010-04-13T13:33:10.000Z", "title": "Diameters in preferential attachment models", "authors": [ "Sander Dommers", "Remco van der Hofstad", "Gerard Hooghiemstra" ], "journal": "Journal of Statistical Physics, 139(1):72-107, (2010)", "doi": "10.1007/s10955-010-9921-z", "categories": [ "math.PR", "math.CO" ], "abstract": "In this paper, we investigate the diameter in preferential attachment (PA-) models, thus quantifying the statement that these models are small worlds. The models studied here are such that edges are attached to older vertices proportional to the degree plus a constant, i.e., we consider affine PA-models. There is a substantial amount of literature proving that, quite generally, PA-graphs possess power-law degree sequences with a power-law exponent \\tau>2. We prove that the diameter of the PA-model is bounded above by a constant times \\log{t}, where t is the size of the graph. When the power-law exponent \\tau exceeds 3, then we prove that \\log{t} is the right order, by proving a lower bound of this order, both for the diameter as well as for the typical distance. This shows that, for \\tau>3, distances are of the order \\log{t}. For \\tau\\in (2,3), we improve the upper bound to a constant times \\log\\log{t}, and prove a lower bound of the same order for the diameter. Unfortunately, this proof does not extend to typical distances. These results do show that the diameter is of order \\log\\log{t}. These bounds partially prove predictions by physicists that the typical distance in PA-graphs are similar to the ones in other scale-free random graphs, such as the configuration model and various inhomogeneous random graph models, where typical distances have been shown to be of order \\log\\log{t} when \\tau\\in (2,3), and of order \\log{t} when \\tau>3.", "revisions": [ { "version": "v3", "updated": "2010-04-13T13:33:10.000Z" } ], "analyses": { "keywords": [ "preferential attachment models", "typical distance", "pa-graphs possess power-law degree sequences", "lower bound", "constant times" ], "tags": [ "journal article" ], "publication": { "journal": "Journal of Statistical Physics", "year": 2010, "month": "Apr", "volume": 139, "number": 1, "pages": 72 }, "note": { "typesetting": "TeX", "pages": 0, "language": "en", "license": "arXiv", "status": "editable", "adsabs": "2010JSP...139...72D" } } }