TTP02-02 Two-loop matrix elements for three jet production: the $n_f$ contribution.

We discuss the calculation of the

   $n_f$-contributions to the two-loop
   amplitude for $ e^+ e^- \rightarrow q g \bar{q}$.
   The calculation uses an efficient method based on nested sums.
   The result is presented in terms of multiple polylogarithms
   with simple arguments, which allow for analytic continuation 
   in a straightforward manner.