Bounds for self-dual codes over Z(4)

New bounds are given for the minimal Hamming and Lee weights of self-dual c odes over ii,. For a self-dual code of length n, the Hamming weight is boun ded above by 4[n/24] + f(n mod 24), for an explicitly given function f; the Lee weight is bounded above by 8[n/24] + g(n mod 24), for a different func tion g. These bounds appear to agree with the full linear programming bound for a wide range of lengths. The proof of these bounds relies on a reducti on to a problem of binary codes, namely that of bounding the minimum dual d istance of a doubly even binary code. (C) 2000 Academic Press.