A central limit theorem for biased random walks on Galton–Watson trees

By Yuval Peres, Ofer Zeitouni. 2006

56 citations recorded by the source corpus.

Let $${\mathcal{T}}$$ be a rooted Galton–Watson tree with offspring distribution {pk} that has p0 = 0, mean m = ∑ kpk > 1 and exponential tails. Consider the λ-biased random walk {Xn}n ≥ 0 on $${\mathcal{T}}$$ ; this is the nearest neighbor random walk which, when at a vertex v with dv offspring, moves closer to the root with probability λ/(λ + dv), and moves to each of the offspring with probability 1/(λ + dv). It is known that this walk has an a.s. constant speed $${\tt v} = \lim_n |X_n|/n$$ (where |Xn| is the distance of Xn from the root), with $${\tt v} > 0$$ for 0 < λ < m and $${\tt v} = 0$$ for λ ≥ m. For all λ ≤ m, we prove a quenched CLT for $$|X_n| - n{\tt v}$$ . (For λ >  m the walk is positive recurrent, and there is no CLT.) The most interesting case by far is λ = m, where the CLT has the following form: for almost every $${\mathcal{T}}$$ , the ratio $$|X_{[nt]}|/\sqrt{n}$$ converges in law as n → ∞ to a deterministic multiple of the absolute value of a Brownian motion. Our approach to this case is based on an explicit description of an invariant measure for the walk from the point of view of the particle (previously, such a measure was explicitly known only for λ = 1) and the construction of appropriate harmonic coordinates.

Subfields: Condensed Matter Physics, Mathematical Physics, Statistics and Probability

View Paper: https://www.semanticscholar.org/paper/81f8ef93cd4dae48aab72e435fa1115da29af1a8

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In Condensed Matter Physics

  1. Marek Tomasz Biskup
  2. Zhan Shi
  3. Thomas Madaule
  4. Elie Aidékon
  5. Rémi Rhodes
  6. Vincent Vargas

In Mathematical Physics

  1. Marek Tomasz Biskup
  2. Zhan Shi
  3. Thomas Madaule
  4. Elie Aidékon
  5. Rémi Rhodes
  6. Vincent Vargas

In Statistics and Probability

  1. Marek Tomasz Biskup
  2. Zhan Shi
  3. Thomas Madaule
  4. Elie Aidékon
  5. Rémi Rhodes
  6. Vincent Vargas

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