  We rederive the conformal anomaly for spin-1/2 fermions by a genuine Feynman
graph calculation, which has not been available so far. Although our
calculation merely confirms a result that has been known for a long time, the
derivation is new, and thus furnishes a method to investigate more complicated
cases (in particular concerning the significance of the quantum trace of the
stress tensor in non-conformal theories) where there remain several outstanding
and unresolved issues.
