Abstract
Given a connected finite graph Γ with a fixed base point O and some graph G with a based point we study random 1-Lipschitz maps of a scaled Γ into G. We are mostly interested in the case where G is a Cayley graph of some finitely generated group, where the construction does not depend on the choice of base points. A particular case of Γ being a graph on two vertices and one edge corresponds to the random walk on G, and the case where Γ is a graph on two vertices and two edges joining them corresponds to Brownian bridge in G. We show, that unlike in the case \({G=\mathbb Z^d}\), the asymptotic behavior of a random scaled mapping of Γ into G may differ significantly from the asymptotic behavior of random walks or random loops in G. In particular, we show that this occurs when G is a free non-Abelian group. Also we consider the case when G is a wreath product of \({\mathbb Z}\) with a finite group. To treat this case we prove new estimates for transition probabilities in such wreath products. For any group G generated by a finite set S we define a functor E from category of finite connected graphs to the category of equivalence relations on such graphs. Given a finite connected graph Γ, the value E G,S (Γ) can be viewed as an asymptotic invariant of G.
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Erschler, A. Random mappings of scaled graphs. Probab. Theory Relat. Fields 144, 543–579 (2009). https://doi.org/10.1007/s00440-008-0154-x
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DOI: https://doi.org/10.1007/s00440-008-0154-x
Keywords
- Random walks on groups
- Brownian bridges
- Free groups
- Lamplighter groups
- Random graph homomorphism
- Lipschitz maps
Mathematics Subject Classification (2000)
- 20F69
- 20F65
- 20P05
- 60B15