Power-law Polya’s urn and fractional Brownian motion

نویسندگان

  • Alan Hammond
  • Scott Sheffield
چکیده

We introduce a natural family of random walks Sn on Z that scale to fractional Brownian motion. The increments Xn := Sn − Sn−1 ∈ {±1} have the property that given {Xk : k < n}, the conditional law of Xn is that of Xn−kn , where kn is sampled independently from a fixed law μ on the positive integers. When μ has a roughly power law decay (precisely, when μ lies in the domain of attraction of an α-stable subordinator, for 0 < α < 1/2) the walks scale to fractional Brownian motion with Hurst parameter α+1/2. The walks are easy to simulate and their increments satisfy an FKG inequality. In a sense we describe, they are the natural “fractional” analogs of simple random walk on Z .

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تاریخ انتشار 2009