Exercise 8.2. Suppose the dynamics of the forward rate are given by (8.7) with
f_(0)^(T)=lambda _(0)+lambda _(1)e^(-gamma T)-(eta ^(2))/(2gamma ^(2))(1-e^(-gamma T))^(2),
sigma _(t)^(T)=eta e^(-gamma (T-t)).
Show that the short rate R admits the form
R_(t)=g(t,R_(0))+int_0^t h(s;t)dW_tilde(W)_(s),
and identify the functions g and h.