Ternary associator, ternary commutator and ternary Lie algebra at cube roots of unity

Abstract

We extend the concepts of the associator and commutator from algebras with a binary multiplication law to algebras with a ternary multiplication law using cube roots of unity. By analogy with the Jacobi identity for the binary commutator, we derive an identity for the proposed ternary commutator. While the Jacobi identity is based on the cyclic permutation group of three elements $\mathbb Z_3$, the identity we establish for the ternary commutator is based on the general affine group $GA(1,5)$. We introduce the notion of a ternary Lie algebra at cube roots of unity. A broad class of such algebras is constructed using associative ternary multiplications of rectangular and cubic matrices. Furthermore, a complete classification of non-isomorphic two-dimensional ternary Lie algebras at cube roots of unity is obtained.