Ternary codes of minimum weight 6 and the classification of the self-dual codes of length 20

Self-orthogonal ternary codes of minimum weight may be analyzed in a straightforward manner using the theory of glueing introduced in earlier papers. The present paper describes a method for studying codes of minimum weight : the supports of the words of weight form what is called a center set. Associated with each center set is a graph, and all the graphs that can arise in this way are known. These techniques are used to classify the ternary self-dual codes of length : there are inequivalent codes, of which are indecomposable. Six of the codes have minimum weight .