The sedenions are obtained by applying theCayley–Dickson construction to theoctonions, which can be mathematically expressed as.[1] As such, the octonions areisomorphic to asubalgebra of the sedenions. Unlike the octonions, the sedenions are not analternative algebra. Applying the Cayley–Dickson construction to the sedenions yields a 32-dimensional algebra, called thetrigintaduonions or sometimes the 32-nions.[2]
The termsedenion is also used for other 16-dimensional algebraic structures, such as a tensor product of two copies of thebiquaternions, or the algebra of4 × 4matrices over the real numbers, or that studied bySmith (1995).
A visualization of a 4D extension to the cubicoctonion,[3] showing the 35 triads ashyperplanes through the real vertex of the sedenion example given
Every sedenion is alinear combination of the unit sedenions,,,, ...,,which form abasis of thevector space of sedenions. Every sedenion can be represented in the form
Addition and subtraction are defined by the addition and subtraction of corresponding coefficients and multiplication isdistributive over addition.
Like other algebras based on theCayley–Dickson construction, the sedenions contain the algebra they were constructed from. So they contain the octonions (generated by to in the table below), and therefore also thequaternions (generated by to),complex numbers (generated by and) and real numbers (generated by).
Likeoctonions,multiplication of sedenions is neithercommutative norassociative. However, in contrast to the octonions, the sedenions do not even have the property of beingalternative. They do, however, have the property ofpower associativity, which can be stated as that, for any element of, the power is well defined. They are alsoflexible.
The sedenions have a multiplicativeidentity element and multiplicative inverses, but they are not adivision algebra because they havezero divisors: two nonzero sedenions can be multiplied to obtain zero, for example. Allhypercomplex number systems after sedenions that are based on the Cayley–Dickson construction also contain zero divisors.
An illustration of the structure ofPG(3,2) that provides the multiplication law for sedenions, as shown bySaniga, Holweck & Pracna (2015). Any three points (representing three sedenion imaginary units) lying on the same line are such that the product of two of them yields the third one, sign disregarded.
The sedenions are not fully anti-associative. Choose any four generators, and. The following 5-cycle shows that these five relations cannot all be anti-associative.
In particular, in the table above, using and the last expression associates.
The particular sedenion multiplication table shown above is represented by 35 triads. The table and its triads have been constructed from anoctonion represented by the bolded set of 7 triads usingCayley–Dickson construction. It is one of 480 possible sets of 7 triads (one of two shown in the octonion article) and is the one based on the Cayley–Dickson construction ofquaternions from two possible quaternion constructions from thecomplex numbers. The binary representations of the indices of these triplesbitwise XOR to 0. These 35 triads are:
Moreno (1998) showed that the space of pairs of norm-one sedenions that multiply to zero ishomeomorphic to the compact form of the exceptionalLie groupG2. (Note that in his paper, a "zero divisor" means apair of elements that multiply to zero.)
Guillard & Gresnigt (2019) demonstrated that the three generations ofleptons andquarks that are associated with unbrokengauge symmetry can be represented using the algebra of the complexified sedenions. Their reasoning follows that a primitiveidempotentprojector – where is chosen as animaginary unit akin to for in theFano plane – thatacts on thestandard basis of the sedenions uniquely divides the algebra into three sets ofsplit basis elements for, whose adjointleft actionson themselves generate three copies of theClifford algebra which in turn containminimal left ideals that describe a single generation offermions with unbroken gauge symmetry. In particular, they note thattensor products between normed division algebras generate zero divisors akin to those inside, where for the lack of alternativity and associativity does not affect the construction of minimal left ideals since their underlying split basis requires only two basis elements to be multiplied together, in-which associativity or alternativity are uninvolved. Still, these ideals constructed from an adjoint algebra of left actions of the algebra on itself remain associative, alternative, andisomorphic to a Clifford algebra. Altogether, this permits three copies of to exist inside. Furthermore, these three complexified octonion subalgebras are not independent; they share a common subalgebra, which the authors note could form a theoretical basis forCKM andPMNS matrices that, respectively, describequark mixing andneutrino oscillations.
Sedenion neural networks provide[further explanation needed] a means of efficient and compact expression in machine learning applications and have been used in solving multiple time-series and traffic forecasting problems[5][6] as well ascomputer chess.[7]
Biss, Daniel K.; Christensen, J. Daniel; Dugger, Daniel; Isaksen, Daniel C. (2007). "Large annihilators in Cayley-Dickson algebras II".Boletin de la Sociedad Matematica Mexicana.3:269–292.arXiv:math/0702075.Bibcode:2007math......2075B.