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Paper 1 — Sign-Parity Classification of Zero-Divisors in Cayley–Dickson Algebras

Giovanni Levratti
Independent Researcher, Modena, Italy • ORCID 0009-0000-9804-3452
Series: Zero-Divisors in Cayley–Dickson Algebras — Paper 1
Version: v2 • Year: 2026
DOI: https://doi.org/10.5281/zenodo.20315751
Under Peer Review — Communications in Algebra

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Abstract

We develop a complete structural theory of zero-divisors in the Cayley-Dickson algebras A_n.

The main results are:
(i) an exact closed-form count |ZD(n)| = 336 × C(n-1,3)_2 for all n ≥ 4, where 336 = 2|PSL(2,7)| encodes the Fano-plane symmetry;
(ii) a sign-parity classification via three invariants satisfying π_A·π_B·π_C = -1;
(iii) a proof that the Born Rule axioms admit a unique solution for n ≤ 3 and no solution for n ≥ 4;
(iv) the spectral decomposition Spec(M_a) = {0,1,2} with multiplicities 1:2:1 for every ZD unit;
(v) a full computational classification of all 460,880 zero-divisor elements in A_4.

All open problems PA1-PA5 are resolved unconditionally.

How to Cite
@misc{levratti2026signparity,
  author    = {Levratti, Giovanni},
  title     = {Sign-Parity Classification of Zero-Divisors in Cayley–Dickson Algebras},
  year      = {2026},
  publisher = {Zenodo},
  doi       = {10.5281/zenodo.20315751},
  url       = {https://doi.org/10.5281/zenodo.20315751},
  note      = {Paper 1 in the series Zero-Divisors
               in Cayley--Dickson Algebras, v2}
}