AlgebraLibraryData - Maple Help
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LieAlgebras[AlgebraLibraryData] - retrieve the structure equations for various classical algebras (quaternions, octonions, Clifford algebras, and low dimensional Jordan algebras)

Calling Sequences

   AlgebraLibraryData(AlgType, AlgName, options)

    

Parameters

     AlgType    - a string, "Real", "Complex", "Quaternions", "Octonions", "Clifford(n)", "Jordan(n, Real)", "Jordan(n, Complex)", "Jordan(n, Quaternions)", "Jordan(n, Octonions)" where n is a positive integer

     AlgName    - a name or a string, the frame name for the algebra being created

     options    - the keyword arguments type = "Standard" or type ="Split", version = 1 or version =2, quadraticform = Q where Q is a non-singular symmetric matrix.

  

 

Description

Examples

Description

• 

 The command AlgebraLibraryData retrieves the structure equations for any of the following real algebras: the real numbers , the complex numbers the quaternions the octonions the Clifford algebras on  with respect to the quadratic form , and the Jordan algebras  for small values of .

• 

The keyword argument type ="Split" may be applied to the algebras  to obtain their split forms. The argument type ="Split" can be applied to  to obtain the Jordan algebras defined over the split complex numbers, the split quaternions, or the split octonions.

• 

There are two generally accepted versions of the structure equations for the octonions. These are described in Example 2.

• 

The keyword argument quadraticform = Q can be used create the general Clifford algebras, defined with respect to a quadratic form. See Example 3.

• 

For the following small values of the structure equations have been stored in Maple and are available without computation: for for for for More generally, Jordan algebras can be created using the command JordanMatrices, JordanProduct, and AlgebraData.

Examples

 

Example 1.

We define the quaternions and the split quaternions and compare their multiplication tables:

(2.1)

 

Here are the split quaternions.

H > 

H > 

(2.2)

 

We see that the off-diagonal products in the multiplication tables are the same. For the quaternions while for the split quaternions .

Hs > 

 

Example 2.

Various conventions can be found in the literature for the multiplication table for the octonions, differing by a labeling of the basis elements. The command AlgebraLibraryData provides 2 different conventions. For the first, the multiplication rules are defined by the formula

 

where the are the components of a 3-form determined by These multiplication rules are summarized using the Fano plane mnemonic:

 

 

 

The triple of integers lying on a straight line or circle coincide with the non-zero coefficients of .

(2.3)
O1 > 

 

For the second version, the non-zero components of the 3-form  are

O1 > 

O1 > 

(2.4)
O2 > 

Both versions have split counterparts.

 

Example 3.

Let be a vector space with basis and let be a non-degenerate quadratic form on The Clifford algebra is the algebra generated by products of the vectors subject to the multiplication rules

 

.

 

A vector space basis for the Clifford algebra is the identity and the ordered products , where . The dimension of is The default choice for the quadratic form  is given by the identity matrix .

 

We first display the multiplication tables for

O2 > 

O2 > 

(2.5)
O2 > 

 

We note that the Clifford algebras are always associative.

 

Here is the multiplication table for .

Cl3 > 

O2 > 

O2 > 

(2.6)
O2 > 

 

Finally, we remark that the quaternions  and the Clifford algebra are isomorphic.

O2 > 

O2 > 

(2.7)
O2 > 

 

Example 4.

Here are the structure equations for the Jordan algebra . This is the algebra of 2 × 2 Hermitian matrices with quaternionic entries and the product

Cl3 > 

Cl2 > 

(2.8)
J2 > 

See Also

DifferentialGeometry

AlgebraData

Algebra Inverse

AlgebraNorm

DGsetup

MultiplicationTable

 


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