Directed Graph Representation of Half-Rate Additive Codes over GF(4)
Abstract
We show that (n,2^n) additive codes over GF(4) can be represented as directed graphs. This generalizes earlier results on self-dual additive codes over GF(4), which correspond to undirected graphs. Graph representation reduces the complexity of code classification, and enables us to classify additive (n,2^n) codes over GF(4) of length up to 7. From this we also derive classifications of isodual and formally self-dual codes. We introduce new constructions of circulant and bordered circulant directed graph codes, and show that these codes will always be isodual. A computer search of all such codes of length up to 26 reveals that these constructions produce many codes of high minimum distance. In particular, we find new near-extremal formally self-dual codes of length 11 and 13, and isodual codes of length 24, 25, and 26 with better minimum distance than the best known self-dual codes.
Cite
@article{arxiv.0902.3883,
title = {Directed Graph Representation of Half-Rate Additive Codes over GF(4)},
author = {Lars Eirik Danielsen and Matthew G. Parker},
journal= {arXiv preprint arXiv:0902.3883},
year = {2011}
}
Comments
Presented at International Workshop on Coding and Cryptography (WCC 2009), 10-15 May 2009, Ullensvang, Norway. (14 pages, 2 figures)