Abstract
Consider a closed subgroup Γ of the automorphism group of a homogeneous treeT, and assume that Γ acts transitively on the vertex set. Suppose that μ is a probability measure on Γ which has continuous density with respect to Haar measure and whose support is compact open and generates Γ as a closed semigroup. It is shown that the Martin boundary of Γ with respect to the random walk with law μ coincides with the space of ends ofT. This extends known results for free groups and applies, for example, to the affine group over a non archimedean local field.
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Woess, W. The martin boundary for harmonic functions on groups of automorphisms of a homogeneous tree. Monatshefte für Mathematik 120, 55–72 (1995). https://doi.org/10.1007/BF01470065
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DOI: https://doi.org/10.1007/BF01470065