English

Half-axes in power associative algebras

Rings and Algebras 2018-01-23 v3 Group Theory

Abstract

Let AA be a commutative, non-associative algebra over a field F\mathbb{F} of characteristic 2\ne 2. A half-axis in AA is an idempotent eAe\in A such that ee satisfies the Peirce multiplication rules in a Jordan algebra, and, in addition, the 11-eigenspace of ade{\rm ad}_e (multiplication by ee) is one dimensional. In this paper we consider the identities ()(*) x2x2=x4x^2x^2=x^4 and x3x2=xx4.x^3x^2=xx^4. We show that if identities ()(*) hold strictly in A,A, then one gets (very) interesting identities between elements in the eigenspaces of ade{\rm ad}_e (note that if F>3|\mathbb{F}|>3 and the identities ()(*) hold in A,A, then they hold strictly in AA). Furthermore we prove that if AA is a primitive axial algebra of Jordan type half (i.e., AA is generated by half-axes), and the identities ()(*) hold strictly in A,A, then AA is a Jordan algebra.

Keywords

Cite

@article{arxiv.1707.05906,
  title  = {Half-axes in power associative algebras},
  author = {Yoav Segev},
  journal= {arXiv preprint arXiv:1707.05906},
  year   = {2018}
}

Comments

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R2 v1 2026-06-22T20:51:07.206Z