Sharif Digital Repository

We consider a biased random walk Xn on a Galton-watson tree with leaves in the subballistic regime. We prove that there exists an explicit constant ϒ = ϒ(β) ε (0,1),such that |Xn| is of order n. If Δn be the hitting time of level n, we prove that Δn{n1{ is tight. More ever we show thatΔn{n1{ does not converge in law. We prove that along the sequences npkq Xk\ , Δn{n1{ converges to certain infinity divisible laws. Key tools for the proof are the classical Harris decomposition for Galton-Watson trees, a new variant of regeneration times and the careful analysis of triangular arrays of i.i.d. random variables  

In this dissertation, we investigate the problem of the existence of finite geodetic sequences from point to point (0, n). This has not been proven in the general case. In this dissertation, we present an article that illustrates this question in a particular case of z ^ 2 subspaces whose self and complement are infinite and connected (e.g., slit planes, half-planes, and sectors). Writing x_n for the sequence of boundary vertices, we show that the sequence of geodesics from any point to x_n has an almost sure limit assuming only existence of finite geodesics. For all passage-time configurations, we show existence of a limiting Busemann function. Specializing to the case of the half-plane, we...