{ "id": "cond-mat/0701126", "version": "v3", "published": "2007-01-06T18:14:39.000Z", "updated": "2007-05-01T17:02:29.000Z", "title": "Continuous time random walk and parametric subordination in fractional diffusion", "authors": [ "Rudolf Gorenflo", "Francesco Mainardi", "Alessandro Vivoli" ], "comment": "28 pages, 18 figures. Workshop 'In Search of a Theory of Complexity'. Denton, Texas, August 2005", "journal": "Chaos, Solitons and Fractals, Vol. 34 (2007), pp. 89-103", "categories": [ "cond-mat.stat-mech", "math-ph", "math.MP", "math.PR" ], "abstract": "The well-scaled transition to the diffusion limit in the framework of the theory of continuous-time random walk (CTRW)is presented starting from its representation as an infinite series that points out the subordinated character of the CTRW itself. We treat the CTRW as a combination of a random walk on the axis of physical time with a random walk in space, both walks happening in discrete operational time. In the continuum limit we obtain a generally non-Markovian diffusion process governed by a space-time fractional diffusion equation. The essential assumption is that the probabilities for waiting times and jump-widths behave asymptotically like powers with negative exponents related to the orders of the fractional derivatives. By what we call parametric subordination, applied to a combination of a Markov process with a positively oriented L\\'evy process, we generate and display sample paths for some special cases.", "revisions": [ { "version": "v3", "updated": "2007-05-01T17:02:29.000Z" } ], "analyses": { "keywords": [ "continuous time random walk", "parametric subordination", "space-time fractional diffusion equation", "continuous-time random walk", "non-markovian diffusion process" ], "tags": [ "journal article" ], "publication": { "doi": "10.1016/j.chaos.2007.01.052", "journal": "Chaos Solitons and Fractals", "year": 2007, "month": "Oct", "volume": 34, "number": 1, "pages": 87 }, "note": { "typesetting": "TeX", "pages": 28, "language": "en", "license": "arXiv", "status": "editable", "adsabs": "2007CSF....34...87G" } } }