A large automorphism group decreases the number of computations in the construction of an optimal encoder/decoder pair for linear block code

For a linear block code it is shown how the number of computations needed for the determination of an optimal encoder/decoder pair can be reduced by using the code´s automorphism group. Furthermore, it is shown that the use of an unequal-error-protection-optical generator matrix and a minimum-weight coset leader decoder is suboptimal for a q-ary symmetry channel, but their determination needs less computational effort