Séminaire Lotharingien de Combinatoire, B14Sb (1986).

Arne Dür

The Authomorphism Group of Reed-Solomon Codes

Abstract. A class of maximum distance separable codes is introduced which includes Reed-Solomon codes, extended Reed-Solomon codes, and other cyclic or pseudocyclic MDS codes studied recently. Codes in this class are called `Cauchy codes' because of the special form of their generator matrices. For every Cauchy code the automorphism group and its underlying permutation group are determined. For doubly-extended Reed-Solomon codes over GF(q) the permutation group is the semilinear fractional group P\Gamma L(2,q).

The paper has been finally published under the same title in J. Combin. Theory Ser. A 44 (1987), 69-82.