“…• The complex numbers (C), the quaternions (H), the octonions (O), and the sedenions (S) are the algebras of the main sequence for n = 1, 2, 3, and 4, correspondingly. We refer the reader to [6] for the definition of H and O, and to [13] for that of S. • The split-complex numbers ( Ĉ), the split-quaternions (the coquaternions; Ĥ), and the splitoctonions (the hyperbolic octonions; Ô) are the examples of real low-dimensional split-algebras, all of them being defined in [10].…”