Self-Dual Codes over Z_2xZ_4

Self-dual codes over Z2 ×Z4 are subgroups of Z2 ×Zβ4 that are equal to their orthogonal under an inner-product that relates to the binary Hamming scheme. Three types of self-dual codes are defined. For each type, the possible values α, β such that there exist a code C ⊆ Z 2 ×Z 4 are established. Moreover, the construction of a Z2Z4-linear code for each type and possible pair (α, β) is given. Finally, the standard techniques of invariant theory are applied to describe the weight enumerators for each type. Index Terms Self-dual codes, Type I codes, Type II codes and Z2Z4-additive codes.Self-dual codes, Type I codes, Type II codes and Z2Z4-additive codes.