157 research outputs found
New extremal singly even self-dual codes of lengths and
For lengths and , we construct extremal singly even self-dual codes
with weight enumerators for which no extremal singly even self-dual codes were
previously known to exist. We also construct new inequivalent extremal
doubly even self-dual codes with covering radius meeting the
Delsarte bound.Comment: 13 pages. arXiv admin note: text overlap with arXiv:1706.0169
On self-dual double circulant codes
Self-dual double circulant codes of odd dimension are shown to be dihedral in
even characteristic and consta-dihedral in odd characteristic. Exact counting
formulae are derived for them and used to show they contain families of codes
with relative distance satisfying a modified Gilbert-Varshamov bound.Comment: 8 page
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