“…On the other hand, This equality can be verified straightforwardly by calculation of the partial derivatives of ψ , but its strong justification needs deeper mathematical considerations because the integral in is a stochastic integral defined as a limit in the mean square sense (not in the pointwise sense). We refer to (see also ) for mathematics of this issue, noticing that in the partial differentiation − ∂ / ∂θ can be interpreted as a differential operator − d / d θ on L 2 , which has the domain D ( − d / d θ ) as a collection of all h ∈ L 2 such that h ′ ∈ L 2 and h ( − ϵ ) = 0. The operator − d / d θ generates the strongly continuous semigroup T defined by which is called a semigroup of right translation.…”