English

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

Combinatorics 2014-01-10 v1

Abstract

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) (=n4n13n22)( =\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: mk\in \{m:\ m is odd, 3m35, m17,21}{45,47,75,77,79,159}3\leq m\leq 35,\ m\neq 17,21\}\cup \{45,47,75,77,79,159\}.

Keywords

Cite

@article{arxiv.1401.2022,
  title  = {The completion of optimal $(3,4)$-packings},
  author = {Jingjun Bao and Lijun Ji},
  journal= {arXiv preprint arXiv:1401.2022},
  year   = {2014}
}
R2 v1 2026-06-22T02:42:09.636Z