Balister–Győri–Schelp conjecture on Hadamard pair solutions

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Throughout, all vectors and matrices are over F2\mathbb{F}_2. Fix s⩾2s\geqslant 2 and let M=[v0,…,v2s−1−1]M=[v_0,\ldots,v_{2^{s-1}-1}] be an s×2s−1s\times 2^{s-1} matrix with nonzero columns. Let H=[h0,…,h2s−1]\mathcal{H}=[h_0,\ldots,h_{2^s-1}] be an s×2ss\times 2^s matrix whose columns are precisely the vectors of F2s\mathbb{F}_2^s, each appearing once. A Hadamard pair solution for MM is an ordering of the columns of H\mathcal{H} such that vi=h2i+h2i+1v_i=h_{2i}+h_{2i+1} for every i∈{0,…,2s−1−1}i\in\{0,\ldots,2^{s-1}-1\}.

Balister–Győri–Schelp conjecture. If

∑i=02s−1−1vi=0,\sum_{i=0}^{2^{s-1}-1}v_i=0,

then MM has a Hadamard pair solution.

The zero-sum condition is necessary because the sum of all vectors in F2s\mathbb{F}_2^s is zero. The conjecture asserts that this necessary condition is also sufficient for partitioning F2s\mathbb{F}_2^s into pairs with the prescribed nonzero differences; the supplied source does not state whether it has been resolved.

References

Primary source

Aryeh Lev Zabokritskiy, “Perfect Matchings with Prescribed Differences Beyond Hall: The Two-Hole Problem”, arXiv:2607.08630 (2026).

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