Pullback of rough bundle-valued differential forms #
Pullback precomposes each alternating map with the manifold derivative. Its value fiber
at x is the original fiber at f x, so it works without a trivialization of the value
bundle. Both within-set and unrestricted pullbacks are total; their chain rules carry
the differentiability and unique-derivative hypotheses of Mathlib's mfderivWithin.
For a trivial value bundle, mpullbackWithin and mpullback retain the fixed coefficient
space. On model spaces they agree with precomposition by the Fréchet derivative.
Pullback at x only depends on the germ of f at x, within-set pullback at x only on the
value at x and the germ within the set, and when the derivative of f at x
is surjective it determines the form at f x.
This construction follows Lee, Introduction to Smooth Manifolds, second edition, Chapter 14. The proofs reuse Mathlib's manifold chain rule and alternating-map composition.
Pullback using the derivative within s; the value bundle is pulled back along f.
Instances For
Evaluation of within-set pullback on tangent vectors.
Pullback of a rough form, with values in the pulled-back value bundle.
Instances For
Evaluation of pullback on tangent vectors.
The within-set construction on the whole manifold is ordinary pullback.
Within-set and ordinary pullback agree where the derivatives agree.
Within-set pullback preserves the zero form.
Pullback preserves the zero form.
Within-set pullback distributes over addition.
Pullback distributes over addition.
Within-set pullback commutes with scalar multiplication of the values, by any scalars acting continuously on the fibres and commuting with the real action.
Pullback commutes with scalar multiplication of the values, by any scalars acting continuously on the fibres and commuting with the real action.
Within-set pullback by the identity fixes a form wherever the derivative is unique.
Pullback by the identity fixes a rough form.
The chain rule for bundle-valued pullbacks within sets.
The chain rule for bundle-valued pullbacks when the intermediate set condition holds only locally at the base point.
The chain rule for bundle-valued pullback at one point.
The chain rule on a set, requiring differentiability only at its points and their images.
Pullback reverses composition of differentiable maps.
Pullback of a fixed-coefficient form using the derivative within s.
Instances For
Evaluation of fixed-coefficient within-set pullback on tangent vectors.
Pullback of a fixed-coefficient rough form along the manifold derivative.
Instances For
Evaluation of fixed-coefficient pullback on tangent vectors.
Evaluation of the pullback of a two-form on a pair of tangent vectors.
Pullback within the whole manifold is ordinary pullback.
Within-set and ordinary pullback agree where their derivatives agree.
A form evaluated at a on tangent vectors at b = a moved by tangentSpaceCast is the form
evaluated at b on the original vectors.
Maps that agree near x within s, and at x, pull a form back within s to the same value
at x.
Maps that agree on s pull a form back within s to the same value at each point of s.
Maps that agree near x pull a form back to the same value at x.
If the derivative of f at x is surjective, two forms have the same pullback along f at
x exactly when they agree at f x.
A pullback vanishes at every point where the form vanishes at the image point.
Pullback along a surjective map whose derivatives are all surjective is injective.
Within-set pullback preserves zero.
Pullback preserves zero.
Within-set pullback preserves addition.
Pullback preserves addition.
Pullback preserves subtraction.
Within-set pullback respects scalar multiplication of the coefficients, by any scalars acting continuously on the coefficient space and commuting with the real action.
Pullback respects scalar multiplication of the coefficients, by any scalars acting continuously on the coefficient space and commuting with the real action.
Pullback of a form multiplied pointwise by a scalar function multiplies the pullback by the composite function, for any scalars acting continuously on the coefficient space and commuting with the real action.
Within-set pullback by the identity fixes forms wherever the derivative is unique.
Pullback by the identity fixes forms.
The within-set chain rule for fixed-coefficient forms.
The within-set chain rule for fixed-coefficient forms with a local intermediate-set condition.
The chain rule for fixed-coefficient forms at a point.
The fixed-coefficient chain rule on a set.
Pullback reverses composition of differentiable maps.
Pullback reverses composition with a differentiable map g that does not change where the
inner map f is differentiable. At points where f is not differentiable, the pullbacks of a
form of positive degree both vanish, as the derivative is taken to be zero there; for a form of
degree zero the pullbacks agree by composition of functions.
Pullback of a degree-zero form is composition of its underlying function.
Within-set pullback of a degree-zero form is function composition.
On model spaces, within-set pullback is the flat pullback by the Fréchet derivative.
On model spaces, pullback is the flat pullback by the Fréchet derivative.
The chain rule for precomposition by a map of normed spaces: the pullback along u ∘ L, for a
map L with derivative A at y, is the pullback along u at L y precomposed with A.
The pullback of a form along γ ∘ P, for a continuous linear map P of normed spaces,
vanishes on every family of vectors one of which lies in the kernel of P.
The pullback of a form at x is the form at f x composed with the differential of f,
read as an operator on alternating maps of the model spaces. The two sides agree up to unfolding
the tangent spaces to the model spaces; this is the form in which pullbacks are differentiated.