1 research outputs found

    The completion of optimal (3,4)(3,4)-packings

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    A 3-(n,4,1)(n,4,1) packing design consists of an nn-element set XX and a collection of 44-element subsets of XX, called {\it blocks}, such that every 33-element subset of XX is contained in at most one block. The packing number of quadruples d(3,4,n)d(3,4,n) denotes the number of blocks in a maximum 33-(n,4,1)(n,4,1) packing design, which is also the maximum number A(n,4,4)A(n,4,4) of codewords in a code of length nn, constant weight 44, and minimum Hamming distance 4. In this paper the undecided 21 packing numbers A(n,4,4)A(n,4,4) are shown to be equal to Johnson bound J(n,4,4)J(n,4,4) (=⌊n4⌊nβˆ’13⌊nβˆ’22βŒ‹βŒ‹βŒ‹)( =\lfloor\frac{n}{4}\lfloor\frac{n-1}{3}\lfloor\frac{n-2}{2}\rfloor\rfloor\rfloor) where n=6k+5n=6k+5, k∈{m:Β mk\in \{m:\ m is odd, 3≀m≀35,Β mβ‰ 17,21}βˆͺ{45,47,75,77,79,159}3\leq m\leq 35,\ m\neq 17,21\}\cup \{45,47,75,77,79,159\}
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