The algebraic and geometric classification of right alternative and semi-alternative algebras

Abstract

The algebraic and geometric classifications of complex 3-dimensional right alternative and semi-alternative algebras are given. As corollaries, we have the algebraic and geometric classification of complex 3-dimensional $\mathrm{perm}$, binary $\mathrm{perm}$, associative, $(-1,1)$-, binary $(-1,1)$-, and assosymmetric algebras. In particular, we proved that the first example of non-associative right alternative algebras appears in dimension 3; the first example of non-associative assosymmetric algebras appears in dimension 3; the first example of non-assosymmetric semi-alternative algebras appears in dimension 4; the first example of binary $(-1,1)$-algebras, which is non-$(-1,1)$-, appears in dimension 4; the first example of right alternative algebras, which is not binary $(-1,1)$-, appears in dimension 4; the first example of binary $\mathrm{perm}$ non-$\mathrm{perm}$ algebras appears in dimension 4. As a byproduct, we give an easier answer to problem 2.109 from the Dniester Notebook, previously resolved by Shestakov and Arenas.