Self-dual Codes Over Z₂Z₂[u]

The structure and dual codes of Z2Z2[u] linear codes and Z2Z4-additive codes, respectively, have been studied before. Two different methods of constructions about Z2Z2[u]-additive self-dual codes are analyzed by the author.In addition, the sep-arated condition which is sufficient and necessary is provided. The author proves that type 0 self-dual codes don’t exist by defining three types of Z2Z2[u]-additive self-dual codes:type 0, type Ⅰ, type Ⅱ. And the relevant examples about type I and type Ⅱ are described in detail. This paper also discusses the relation between Z2Z2[u]-additive self-dual codes and Z2Z4-additive self-dual codes and analyzes the construction of two weight Z2Z2[u]-additive self-dual codes.