<t>Hi,Considering that we have:dlambda(t)=(teta(t)-a(t)lambda(t))dt+sigma(t)dW(t)Let P(t,u) be the survaival probability between t and u:P(t,u)=E[exp(-int(t,u,lambda(s))) knowing Ft]explicit expresiion of P(t,u)?Is there any working paper or article dealing with this subject?Thanks in advance Mamok ...