If we assume a discrete set of events, our initial probability distribution function can be given by
wi(0)=δi,0,and its time-development after a given time step Δt=ϵ is
wi(t)=∑jW(j→i)wj(t=0).The continuous analog to wi(0) is
w(x)→δ(x),where we now have generalized the one-dimensional position x to a generic-dimensional vector x. The Kroenecker δ function is replaced by the δ distribution function δ(x) at t=0.