“…The generator of the killed random walk can be formally written as the random Schrödinger operator − 1 2d ∆+∞·½ O , where ∆ is the discrete Laplacian. For this type of operators, various localization phenomena have been predicted and some of them have been rigorously proved; see e.g., [1,12]. In particular, the corresponding parabolic problem in our setting is the discrete time initial-boundary value problem u(n + 1, x) − u(n, x) = 1 2d ∆u(n, x), (n, x) ∈ Z + × (Z d \ O), u(n, x) = 0, (n, x) ∈ Z + × O, u(0, x) = ½ {0} (x), (1.4) and the probability P(S t = x, τ > n) represents its unique bounded solution.…”