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last edited 13 years ago by Bill Page |
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Editor: Bill Page
Time: 2011/05/06 10:17:07 GMT-7 |
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| Note: use new LOP | ||
changed: -)library CARTEN MONAL PROP LIN CALEY -\end{axiom} )library CARTEN MONAL PROP LOP CALEY \end{axiom} changed: -𝐋 := LinearOperator(dim, OVAR [], ℚ) -𝐞:ℒ 𝐋 := basisVectors() -𝐝:ℒ 𝐋 := basisForms() 𝐋 := LinearOperator(OVAR ['0,'1,'2,'3,'4,'5,'6,'7], ℚ) 𝐞:ℒ 𝐋 := basisOut() 𝐝:ℒ 𝐋 := basisIn()
Octonion Algebra Is Frobenius In Just One Way
Linear operators over a 8-dimensional vector space representing octonnion algebra
Ref:
-permuted Frobenius Algebras
Zbigniew Oziewicz (UNAM), Gregory Peter Wene (UTSA)
Frobenius algebras and 2D topological quantum field theories
Joachim Kock
We need the Axiom LinearOperator? library.
(1) -> )library CARTEN MONAL PROP LOP CALEY
CartesianTensor is now explicitly exposed in frame initial CartesianTensor will be automatically loaded when needed from /var/aw/var/LatexWiki/CARTEN.NRLIB/CARTEN Monoidal is now explicitly exposed in frame initial Monoidal will be automatically loaded when needed from /var/aw/var/LatexWiki/MONAL.NRLIB/MONAL Prop is now explicitly exposed in frame initial Prop will be automatically loaded when needed from /var/aw/var/LatexWiki/PROP.NRLIB/PROP LinearOperator is now explicitly exposed in frame initial LinearOperator will be automatically loaded when needed from /var/aw/var/LatexWiki/LOP.NRLIB/LOP CaleyDickson is now explicitly exposed in frame initial CaleyDickson will be automatically loaded when needed from /var/aw/var/LatexWiki/CALEY.NRLIB/CALEY
Use the following macros for convenient notation
-- summation macro Σ(x,i, n)==reduce(+, [x for i in n])
-- list macro Ξ(f,i, n)==[f for i in n]
-- subscript macro sb == subscript
𝐋 is the domain of 8-dimensional linear operators over the rational functions ℚ (Expression Integer), i.e. ratio of polynomials with integer coefficients.
dim:=8
| (1) |
macro ℒ == List
macro ℂ == CaleyDickson
macro ℚ == Expression Integer
𝐋 := LinearOperator(OVAR ['0,'1, '2, '3, '4, '5, '6, '7], ℚ)
| (2) |
𝐞:ℒ 𝐋 := basisOut()
| (3) |
𝐝:ℒ 𝐋 := basisIn()
| (4) |
I:𝐋:=[1]; -- identity for composition
X:𝐋:=[2,1]; -- twist
Now generate structure constants for Octonion Algebra
The basis consists of the real and imaginary units. We use quaternion multiplication to form the "multiplication table" as a matrix. Then the structure constants can be obtained by dividing each matrix entry by the list of basis vectors.
Split-complex, co-quaternions and split-octonions can be specified by Caley-Dickson parameters
--q0:=sb('q, [0])
q0:=1 -- not split-complex
| (5) |
--q1:=sb('q, [1])
q1:=1 -- not co-quaternion
| (6) |
q2:=sb('q, [2])
| (7) |
--q2:=1 -- split-octonion QQ := ℂ(ℂ(ℂ(ℚ,'i, q0), 'j, q1), 'k, q2);
Basis: Each B.i is a octonion number
B:ℒ QQ := map(x +-> hyper x,1$SQMATRIX(dim, ℚ)::ℒ ℒ ℚ)
| (8) |
-- Multiplication table: M:Matrix QQ := matrix Ξ(Ξ(B.i*B.j,i, 1..dim), j, 1..dim)
![]() | (9) |
-- Function to divide the matrix entries by a basis element S(y) == map(x +-> real real real(x/y),M)
-- The result is a nested list ѕ :=map(S,B)::ℒ ℒ ℒ ℚ;
Compiling function S with type CaleyDickson(CaleyDickson(
CaleyDickson(Expression(Integer), i, 1), j, 1), k, q[2]) -> Matrix(
Expression(Integer))-- structure constants form a tensor operator Y := Σ(Σ(Σ(ѕ(i)(k)(j)*𝐞.i*𝐝.j*𝐝.k,i, 1..dim), j, 1..dim), k, 1..dim)
![]() | (10) |
arity Y
| (11) |
matrix Ξ(Ξ((𝐞.i*𝐞.j)/Y,i, 1..dim), j, 1..dim)
>> System error: The value (0 . 0) is not of type UNSIGNED-BYTE
A scalar product is denoted by the (2,0)-tensor
U:=Σ(Σ(script('u, [[], [i, j]])*𝐝.i*𝐝.j, i, 1..dim), j, 1..dim)
![]() | (12) |
We say that the scalar product is associative if the tensor equation holds:
Y = Y
U U
In other words, if the (3,0)-tensor:
![]() |
| (13) |
Using the LinearOperator? domain in Axiom and some carefully chosen symbols we can easily enter expressions that are both readable and interpreted by Axiom as "graphical calculus" diagrams describing complex products and compositions of linear operators.
ω:𝐋 :=(Y*I)/U - (I*Y)/U;
>> System error: The value (0 . 0) is not of type UNSIGNED-BYTE
An algebra with a non-degenerate associative scalar product is called a [Frobenius Algebra]?.
We may consider the problem where multiplication Y is given,
and look for all associative scalar products
This problem can be solved using linear algebra.
)expose MCALCFN
MultiVariableCalculusFunctions is now explicitly exposed in frame initial J := jacobian(ravel ω,concat map(variables, ravel U)::ℒ Symbol);
u := transpose matrix [concat map(variables,ravel U)::ℒ Symbol];
J::OutputForm * u::OutputForm = 0
| (14) |
nrows(J),ncols(J)
| (15) |
The matrix J transforms the coefficients of the tensor
into coefficients of the tensor
. We are looking for
the general linear family of tensors
such that
J transforms
into
for any such
.
If the null space of the J matrix is not empty we can use
the basis to find all non-trivial solutions for U:
Ñ:=nullSpace(J);
ℰ:=map((x,y)+->x=y, concat map(variables, ravel U), entries Σ(sb('p, [i])*Ñ.i, i, 1..#Ñ) )
![]() | (16) |
This defines a family of Frobenius algebras:
zero? eval(ω,ℰ)
| (17) |
The pairing is necessarily diagonal!
Ų:𝐋 := eval(U,ℰ)
![]() | (18) |
matrix Ξ(Ξ((𝐞.i 𝐞.j)/Ų,i, 1..dim), j, 1..dim)
>> System error: The value (0 . 0) is not of type UNSIGNED-BYTE
The scalar product must be non-degenerate:
Ů:=determinant Ξ(Ξ(retract((𝐞.i * 𝐞.j)/Ų),j, 1..dim), i, 1..dim)
>> System error: The value (0 . 0) is not of type UNSIGNED-BYTE
Co-pairing
Solve the [Snake Relation]? as a system of linear equations.
Um:=matrix Ξ(Ξ((𝐞.i*𝐞.j)/Ų,i, 1..dim), j, 1..dim)
>> System error: The value (0 . 0) is not of type UNSIGNED-BYTE
Check "dimension" and the snake relations.
d:𝐋:=
Ω /
X /
Ų
>> System error:
The value
(1 . "failed")
is not of type
UNSIGNED-BYTE
Co-algebra
Compute the "three-point" function and use it to define co-multiplication.
W:=(Y,I)/Ų
>> System error: The value (0 . 0) is not of type UNSIGNED-BYTE
test
( I Ω ) /
( Y I ) = λ
>> System error:
The value
(1 . "failed")
is not of type
UNSIGNED-BYTE
Octonion algebra fails the Frobenius Condition!
Χ :=
Y /
λ
>> System error:
The value
(0 . 1)
is not of type
UNSIGNED-BYTE
Perhaps this is not too surprising since Octonion algebra is non-associative. Nevertheless Octonions are "Frobenius" in a more general sense because there is a non-degenerate associative pairing.
i = Unit of the algebra
i:=𝐞.1
| (19) |
test
i /
λ = Ω
>> System error:
The value
(0 . 1)
is not of type
UNSIGNED-BYTE
Handle
H:𝐋 :=
λ /
X /
Y
>> System error:
The value
(1 . "failed")
is not of type
UNSIGNED-BYTE
i U
ι:𝐋:=
( i I ) /
( Ų )
>> System error:
The value
(0 . 0)
is not of type
UNSIGNED-BYTE
Y=U ι
test
Y /
ι = Ų
>> System error:
The value
(0 . 1)
is not of type
UNSIGNED-BYTE
For example:
ex1:=[q[2]=1,p[1]=1]
| (20) |
Ų0:𝐋 :=eval(Ų,ex1)
![]() | (21) |
Ω0:𝐋 :=eval(Ω,ex1)$𝐋
| (22) |
λ0:𝐋 :=eval(λ,ex1)$𝐋
| (23) |
H0:𝐋 :=eval(H,ex1)$𝐋
| (24) |