Title
The codes and the lattices of Hadamard matrices
Abstract
It has been observed by Assmus and Key as a result of the complete classification of Hadamard matrices of order 24, that the extremality of the binary code of a Hadamard matrix H of order 24 is equivalent to the extremality of the ternary code of H^T. In this note, we present two proofs of this fact, neither of which depends on the classification. One is a consequence of a more general result on the minimum weight of the dual of the code of a Hadamard matrix. The other relates the lattices obtained from the binary code and the ternary code. Both proofs are presented in greater generality to include higher orders. In particular, the latter method is also used to show the equivalence of (i) the extremality of the ternary code, (ii) the extremality of the Z"4-code, and (iii) the extremality of a lattice obtained from a Hadamard matrix of order 48.
Year
DOI
Venue
2012
10.1016/j.ejc.2011.11.007
Eur. J. Comb.
Keywords
Field
DocType
complete classification,hadamard matrix,binary code,hadamard matrix h,minimum weight,latter method,greater generality,leech lattice,higher order,ternary code,even unimodular lattice. 1,self-dual code,general result,. hadamard matrix
Discrete mathematics,Hadamard's maximal determinant problem,Combinatorics,Hadamard matrix,Hadamard product,Ternary Golay code,Hadamard three-lines theorem,Hadamard's inequality,Complex Hadamard matrix,Hadamard code,Mathematics
Journal
Volume
Issue
ISSN
33
4
0195-6698
Citations 
PageRank 
References 
2
0.46
9
Authors
2
Name
Order
Citations
PageRank
Akihiro Munemasa111426.25
Hiroki Tamura27221.29