Self-dual Codes over the Kleinian Four Group
Abstract
We introduce self-dual codes over the Kleinian four group K = Z2 × Z2 for a natural quadratic form on Kn and develop the theory. Topics studied are: weight enumerators, mass formulas, classification up to length 8, neighbourhood graphs, extremal codes, shadows, generalized t-designs, lexicographic codes, the Hexacode and its odd and shorter cousin, automorphism groups, marked codes. Kleinian codes form a new and natural fourth step in a series of analogies between binary codes, lattices and vertex operator algebras. This analogy will be emphasized and explained in detail.
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