from cs.IT updates on arXiv.org http://arxiv.org/abs/1207.3384
In this paper we give the structure of constacyclic codes over formal power
series and chain rings. We also present necessary and sufficient conditions on
the existence of MDS codes over principal ideal rings. These results allow for
the construction of infinite families of MDS self-dual codes over finite chain
rings, formal power series and principal ideal rings.