Formulation of the trapping problem 905 k Xi s First-passage time(FPT) k Markov chain F(X1=1)=∑ F(Xn,=t-1) (g) Xi  First-passage time (FPT)  Markov chain = = = = − Ng v v i i v i F X t d g a F X t 1 ( 1) ( ) ( ) Formulation of the trapping problem 20:19:48