Non-degeneracy of the pairing (snake relation)
Ref:
We use the Axiom LinearOperator? library
axiom
)library CARTEN MONAL PROP LOP
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
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LinearOperator is now explicitly exposed in frame initial
LinearOperator will be automatically loaded when needed from
/var/zope2/var/LatexWiki/LOP.NRLIB/LOP
and some convenient notation
axiom
macro Σ(x,i,n)==reduce(+,[x for i in n])
Type: Void
axiom
macro Ξ(f,i,n)==[f for i in n]
Type: Void
axiom
macro sb == subscript
Type: Void
axiom
macro sp == superscript
Type: Void
Let 𝐋 be the domain of 2-dimensional linear operators
axiom
dim:=2
axiom
macro ℒ == List
Type: Void
axiom
macro ℚ == Expression Integer
Type: Void
axiom
𝐋 := LinearOperator(OVAR ['1,'2], ℚ)
Type: Type
axiom
𝐞:ℒ 𝐋 := basisOut()
Type: List(LinearOperator
?(OrderedVariableList
?([1,
2]),
Expression(Integer)))
axiom
𝐝:ℒ 𝐋 := basisIn()
Type: List(LinearOperator
?(OrderedVariableList
?([1,
2]),
Expression(Integer)))
axiom
I:𝐋:=[1] -- identity for composition
Type: LinearOperator
?(OrderedVariableList
?([1,
2]),
Expression(Integer))
axiom
X:𝐋:=[2,1] -- twist
Type: LinearOperator
?(OrderedVariableList
?([1,
2]),
Expression(Integer))
Pairing
A scalar product (pairing) is represented by
axiom
U:=Σ(Σ(sp('u,[i,j])*𝐝.i*𝐝.j, i,1..dim), j,1..dim)
Type: LinearOperator
?(OrderedVariableList
?([1,
2]),
Expression(Integer))
In general we do not require that it be symmetric.
Co-pairing
Solve the "twisted snake relation" as a system of linear equations.
axiom
Ω:𝐋:=Σ(Σ(sb('u,[i,j])*𝐞.i*𝐞.j, i,1..dim), j,1..dim)
Type: LinearOperator
?(OrderedVariableList
?([1,
2]),
Expression(Integer))
axiom
Í :=
( I Ω ) /
( I X ) /
( U I )
Type: LinearOperator
?(OrderedVariableList
?([1,
2]),
Expression(Integer))
axiom
Ì:=
( Ω I ) /
( X I ) /
( I U )
Type: LinearOperator
?(OrderedVariableList
?([1,
2]),
Expression(Integer))
axiom
equate(f,g)==map((x,y)+->(x=y),ravel f, ravel g);
Type: Void
axiom
eq1:=equate(Í,I)
axiom
Compiling function equate with type (LinearOperator(
OrderedVariableList([1,2]),Expression(Integer)),LinearOperator(
OrderedVariableList([1,2]),Expression(Integer))) -> List(Equation
(Expression(Integer)))
Type: List(Equation(Expression(Integer)))
axiom
eq2:=equate(Ì,I)
Type: List(Equation(Expression(Integer)))
axiom
snake:=solve(concat(eq1,eq2),concat Ξ(Ξ(sb('u,[i,j]), i,1..dim), j,1..dim));
Type: List(List(Equation(Expression(Integer))))
axiom
if #snake ~= 1 then error "no solution"
Type: Void
axiom
Ω:=eval(Ω,snake(1))
Type: LinearOperator
?(OrderedVariableList
?([1,
2]),
Expression(Integer))
axiom
matrix Ξ(Ξ(Ω/(𝐝.i*𝐝.j), i,1..dim), j,1..dim)
Type: Matrix(LinearOperator
?(OrderedVariableList
?([1,
2]),
Expression(Integer)))
This is equivalent to a matrix inverse (transposed!)
axiom
Um:=matrix Ξ(Ξ((𝐞.i*𝐞.j)/U, i,1..dim), j,1..dim)
Type: Matrix(LinearOperator
?(OrderedVariableList
?([1,
2]),
Expression(Integer)))
axiom
mU:=inverse map(retract,Um)
Type: Union(Matrix(Expression(Integer)),...)
axiom
Ωm:=Σ(Σ(mU(i,j)*(𝐞.i*𝐞.j), i,1..dim), j,1..dim)
Type: LinearOperator
?(OrderedVariableList
?([1,
2]),
Expression(Integer))
axiom
-- compare
test(Ω=Ωm)
Type: Boolean
Check that the twisted snake relation holds
axiom
test
( I Ω ) /
( I X ) /
( U I ) = I
Type: Boolean
axiom
test
( Ω I ) /
( X I ) /
( I U ) = I
Type: Boolean
Dimension
Since the "snake" is twisted, dimension is as expected.
axiom
d:=
Ω /
U
Type: LinearOperator
?(OrderedVariableList
?([1,
2]),
Expression(Integer))
This "twisted dimension " depends on !
axiom
d':=
Ω /
X /
U
Type: LinearOperator
?(OrderedVariableList
?([1,
2]),
Expression(Integer))