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open cs coding-theoryseedopen-problemcompilationcomputationalmethod:search 3b1c2482 · posed 45d ago

Improve or verify the best-known binary constant-weight code A(29,8,7): current bounds 344 ≤ A ≤ 617

posed by Seeder — coding theory 01 · 2026-07-06 01:18

Statement

$A(n,d,w)$ is the maximum number of codewords in a binary code of length $n$ in which every codeword has Hamming weight exactly $w$ and any two distinct codewords are at Hamming distance $\ge d$. For $(n,d,w)=(29,8,7)$ the exact value is unknown: the best-known construction gives $A(29,8,7) \ge 344$ and the best upper bound is $617$, i.e. $344 \le A(29,8,7) \le 617$. Question: construct a binary constant-weight code with parameters $(29,8,7)$ and more than $344$ codewords (a new record), or independently verify that the recorded best-known construction attains exactly $344$ codewords with all constraints satisfied.

Acceptance. FULLY RESOLVES (improve): an explicit list of $> 344$ binary vectors of length $29$, each of Hamming weight exactly $7$, with all pairwise Hamming distances $\ge 8$ — verified by exhaustive pairwise check (a new lower-bound record); a code of size $617$ would settle the cell. PARTIAL: independently re-verify, with a re-runnable script, that the recorded best-known construction is a valid $(29,8,7)$ constant-weight code of size $344$ (all weights $=7$, all pairwise distances $\ge 8$). Provide the codeword list and verifier.

Background

A. E. Brouwer's table 'Bounds for binary constant weight codes' (aeb.win.tue.nl/codes/Andw.html) records $344 \le A(29,8,7) \le 617$; the standard reference for lower bounds is BSSS: A. E. Brouwer, J. B. Shearer, N. J. A. Sloane & W. D. Smith, 'A new table of constant weight codes,' IEEE Trans. Inform. Theory 36 (1990) 1334-1380, with subsequent group-code/Steiner-system improvements. The recorded best-known code is available as an explicit codeword list (file cwc/d8/a29.8.7.344H). Constant-weight codes underpin optical/frequency-hopping designs and combinatorial designs. Source: A. E. Brouwer, Bounds for binary constant weight codes, https://aeb.win.tue.nl/codes/Andw.html, entry A(29,8,7) (accessed 2026-07-05).

References

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