Wiener process: Difference between revisions

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Update reference to definition of Wiener process to 5th ed. of Durrett
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Another characterisation of a Wiener process is the [[definite integral]] (from time zero to time ''t'') of a zero mean, unit variance, delta correlated ("white") [[Gaussian process]].{{citation needed|date=October 2015}}
 
The Wiener process can be constructed as the [[scaling limit]] of a [[random walk]], or other discrete-time stochastic processes with stationary independent increments. This is known as [[Donsker's theorem]]. Like the random walk, the Wiener process is recurrent in one or two dimensions (meaning that it returns almost surely to any fixed [[neighborhood (mathematics)|neighborhood]] of the origin infinitely often) whereas it is not recurrent in dimensions three and higher.<ref>{{citationcite web needed|datetitle=April 2013Pólya's Random Walk Constants |website= Wolfram Mathworld| url = https://mathworld.wolfram.com/PolyasRandomWalkConstants.html}}.</ref> Unlike the random walk, it is [[scale invariance|scale invariant]], meaning that
 
:<math>\alpha^{-1}W_{\alpha^2 t}</math>