On the binary self-dual codes with an automorphism of order 2 (Q1364208)

This paper examines some general properties of binary self-dual codes with an automorphism of order 2 and without fixed points. These results are applied to extremal codes. In particular, two construction techniques are presented for such codes. These techniques are used to obtain new extremal [40, 20, 8], [42, 21, 8], [44, 22, 8] and [64, 32, 12] binary self-dual codes. The weight enumerators for these codes were previously not known to exist.