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Small Matrices with Small Inverses: Unimodular Zerofree Cases

Combinatorics 2026-05-13 v3 Discrete Mathematics Number Theory

Abstract

We consider unimodular matrices MM such that neither MM nor M1M^{-1} contain zero entries. Matrices typically exhibit a trade-off: small MM imply large M1M^{-1}. We investigate rare cases where both remain small, classify these matrices up to symmetry, and discuss aspects of this balanced setting.

Keywords

Cite

@article{arxiv.2605.03691,
  title  = {Small Matrices with Small Inverses: Unimodular Zerofree Cases},
  author = {Steven Finch},
  journal= {arXiv preprint arXiv:2605.03691},
  year   = {2026}
}

Comments

11 pages; proof of 2x2 counting formula (Euler totient-based) and more empirical results in Addendum

R2 v1 2026-07-01T12:50:44.371Z