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last edited 11 years ago by Bill Page |
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Editor: Bill Page
Time: 2011/04/26 23:35:34 GMT-7 |
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Note: update |
removed: -o:𝐋:=1; -- identity for product removed: -Note: The only purpose of the o symbols on the left above is to serve as a constant left-side margin as required by Axiom. The symbols on the right describe the relation between row. - changed: -In general the pairing is not symmetric! The pairing is necessarily diagonal! removed: -This is the most general form of the "dot product" of two quaternions -\begin{axiom} -(a*b)/Ų -(a*a)/Ų -\end{axiom} - changed: - o Ω / - o X / - o Ų o Ω / X / Ų changed: - o Ω Ω I / - o I Y I I / - o I X I / - o I I Ų o - -\begin{axiom} ( Ω Ω I ) / ( I Y I I ) / ( I X I ) / ( I I Ų ) \begin{axiom} changed: - o i / - o λ = Ω - -\end{axiom} i / λ = Ω \end{axiom} changed: - o λ o / - o Y o - -\end{axiom} λ / Y \end{axiom} changed: - o i I / - o Ų o ( i I ) / ( Ų ) changed: - o Y / - o ι o = Ų - -\end{axiom} Y / ι = Ų \end{axiom}
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.
)library CARTEN MONAL PROP LIN CALEY
CartesianTensor is now explicitly exposed in frame initial CartesianTensor will be automatically loaded when needed from /var/zope2/var/LatexWiki/CARTEN.NRLIB/CARTEN Monoidal is now explicitly exposed in frame initial Monoidal will be automatically loaded when needed from /var/zope2/var/LatexWiki/MONAL.NRLIB/MONAL Prop is now explicitly exposed in frame initial Prop will be automatically loaded when needed from /var/zope2/var/LatexWiki/PROP.NRLIB/PROP LinearOperator is now explicitly exposed in frame initial LinearOperator will be automatically loaded when needed from /var/zope2/var/LatexWiki/LIN.NRLIB/LIN CaleyDickson is now explicitly exposed in frame initial CaleyDickson will be automatically loaded when needed from /var/zope2/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(dim,OVAR [], ℚ)
(2) |
𝐞:ℒ 𝐋 := basisVectors()
(3) |
𝐝:ℒ 𝐋 := basisForms()
(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, *01q(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)
(12) |
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)
(13) |
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:
(14) |
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;
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
(15) |
nrows(J),ncols(J)
(16) |
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) )
(17) |
This defines a family of Frobenius algebras:
zero? eval(ω,ℰ)
(18) |
The pairing is necessarily diagonal!
Ų:𝐋 := eval(U,ℰ)
(19) |
matrix Ξ(Ξ((𝐞.i 𝐞.j)/Ų,i, 1..dim), j, 1..dim)
(20) |
The scalar product must be non-degenerate:
Ů:=determinant Ξ(Ξ(retract((𝐞.i * 𝐞.j)/Ų),j, 1..dim), i, 1..dim)
(21) |
factor Ů
(22) |
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)
(23) |
mU:=transpose inverse map(retract,Um)
(24) |
Ω:=Σ(Σ(mU(i,j)*(𝐞.i*𝐞.j), i, 1..dim), j, 1..dim)
(25) |
matrix Ξ(Ξ(Ω/(𝐝.i*𝐝.j),i, 1..dim), j, 1..dim)
(26) |
Check "dimension" and the snake relations.
d:𝐋:= Ω / X / Ų
(27) |
test ( I Ω ) / ( Ų I ) = I
(28) |
test ( Ω I ) / ( I Ų ) = I
(29) |
Co-algebra
This expression is expensive to compute:
λ:𝐋 := ( Ω Ω I ) / ( I Y I I ) / ( I X I ) / ( I I Ų )
λ:𝐋 := ( I Ω ) / ( Y I )
(30) |
test ( Ω I ) / ( I Y ) = λ
(31) |
It takes to long to computer here but it turns out that Octonion algebra fails the Frobenius Condition::
\begin{axiom}
Χ := Y / λ
test ( λ I ) / ( I Y ) = Χ
test ( I λ ) / ( Y I ) = Χ
\end{axiom}
Perhaps this is not surprising since Octonion algebra is not associative. Nevertheless it is "Frobenius" in a more general sense because there is a non-degenerate associative pairing and co-pairing.
i = Unit of the algebra
i:=𝐞.1
(32) |
test i / λ = Ω
(33) |
Handle
H:𝐋 := λ / Y
(34) |
i U
ι:𝐋:= ( i I ) / ( Ų )
(35) |
Y=U ι
test Y / ι = Ų
(36) |
For example:
ex1:=[q[2]=1,p[1]=1]
(37) |
Ų0:𝐋 :=eval(Ų,ex1)
(38) |
Ω0:𝐋 :=eval(Ω,ex1)$𝐋
(39) |
λ0:𝐋 :=eval(λ,ex1)$𝐋
(40) |
H0:𝐋 :=eval(H,ex1)$𝐋
(41) |