running head: random walk killed on a finite set key words: two-dimensional random walk; exterior domain; transition probability; overshoot estimates AMS Subject classification (2010): Primary 60G50, Secondary 60J45.
AbstractWe study asymptotic behavior, for large time n, of the transition probability of a two-dimensional random walk killed when entering into a non-empty finite subset A. We show that it behaves like 4ũ A (x)ũ −A (−y)(lg n) −2 p n (y − x) for large n, uniformly in the parabolic regime |x| ∨ |y| = O( √ n), where p n (y − x) is the transition kernel of the random walk (without killing) andũ A is the unique harmonic function in the 'exterior of A' satisfying the boundary conditionũ A (x) ∼ lg |x| at infinity.