Skip to main content
6 of 8
added 79 characters in body
Thomas Kojar
  • 5.5k
  • 2
  • 19
  • 41

Wiener measure of hitting sets A,B but not C

I am trying to formulate the measure of event

$E=\{B[0\infty)\cap A,B \neq \varnothing$ and $B[0\infty)\cap C= \varnothing\}$,

where $B[0\infty)$ is a Brownian path and $A,B,C$ are pairwise disjoint compact non-empty sets. I am looking for $\mu_{W}(E)$. Any ideas?

One guess is:

$\mu_{W}(E)=\int_{t_{1}}^{\infty}\int_{0}^{\infty} \int_{B} \int_{A} \int_{\mathbb{R}^{d}/(A\cup B)}p(x_{1},x_{2},t_{1})p(x_{2},x_{3},t_{2}) dx_{1}dx_{2}dx_{3}dt_{1}dt_{2}+ $

$+\int_{t_{1}}^{\infty}\int_{0}^{\infty} \int_{A} \int_{B} \int_{\mathbb{R}^{d}/(A\cup B)}p(x_{1},x_{2},t_{1})p(x_{2},x_{3},t_{2}) dx_{1}dx_{2}dx_{3}dt_{1}dt_{2}-$

$-\int_{0}^{\infty}\int_{C} \int_{\mathbb{R}^{d}/C} p(x_{1},x_{2},t_{1}) dx_{1}dx_{2}dt_{1}$

The first term is hitting A and then B, the second is the converse and the last term is hitting C.

The inner integral is the startpoint of the Brownian motion. For the first two terms ,the outer integral has $t_{1}$ as the startpoint, to denote the transition from A to B.

thanks Ilya. Still I would appreciate if someone can give a precise answer.

Thomas Kojar
  • 5.5k
  • 2
  • 19
  • 41