Cyclic and negacyclic codes over finite chain rings

The structures of cyclic and negacyclic codes of length n and their duals over a finite chain ring (R) over bar are established when n is not divisible by the characteristic of the residue field (R) over bar. Some cases where n is divisible by the characteristic of the residue field (R) over bar are also considered. Namely, the structure of negacyclic codes of length 2(t) over Z(2m) and that of their duals are derived.