Classification conjecture for full-dimensional thick te-interlaces

A thick te-interlace is a totally equimodular interlace satisfying the paper's thickness condition; a matrix is full-dimensional when it has the full dimension specified by that condition. Two matrices are equivalent up to resigning and permuting rows and columns.

Classification conjecture. There are only two full-dimensional thick te-interlaces, up to resigning or permuting rows and columns:

[1111111111111111]and[111111111111111111111111111111111111].\left[\begin{array}{rrrr} 1&1&1&1\\ 1&-1&-1&1\\ 1&-1&1&-1\\ 1&1&-1&-1 \end{array}\right] \quad\text{and}\quad \left[\begin{array}{rrrrrr} 1&1&1&1&1&1\\ 1&1&1&1&-1&-1\\ 1&1&1&-1&-1&1\\ 1&1&-1&-1&1&1\\ 1&-1&-1&1&1&1\\ 1&-1&1&1&1&-1 \end{array}\right].

The conjecture is motivated by a brute-force computer enumeration showing that there are no thick te-interlaces of size 88; the classification of all full-dimensional thick te-interlaces remains open.

Sources & referencesView supporting material

Primary source

Patrick Chervet, Roland Grappe and Mathieu Vallée, “Totally equimodular matrices: decomposition and triangulation”, arXiv:2504.05930 (2025).

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