  We correct errors in Section III-B of the above-titled paper. The corrections
are related to the joint distribution of the inputs to the main decoder which
corresponds to a branch in the code trellis for the main decoder. Note that as
far as the distribution of the input corresponding to a single code symbol is
concerned, the results in Section III-B are correct. We have noticed that alpha
in Proposition 12 (beta in Proposition 14) has another meaning, which has made
it possible to derive the joint distribution of the inputs corresponding to the
whole branch. Corrections are based on this important observation.
