Smooth bundle-valued differential forms #
This file packages smooth sections of the bundle of alternating maps on tangent fibres. The
underlying rough form remains an unbundled dependent function, while IsSmoothBundleForm records
that its graph is a smooth section of the alternating bundle. The corresponding Submodule
provides the bundled carrier SmoothBundleForm; fixed coefficients are the SmoothForm
specialization. These carriers are the input for smooth wedge products and pullbacks.
The degree-two evaluation API below evaluates forms on ordered pairs and exposes real-valued fibres as alternating bilinear forms.
In the trivialization at any point, the fiber coordinate of a form at y is the form pulled back
along the inverse tangent trivialization at y
(FiberBundle.trivializationAt_continuousAlternatingMap_apply_snd),
with no chart-domain hypothesis. Hence a form is C^n exactly when its values on the frames of
these trivializations are (TauCeti.isSmoothForm_iff_forall_contMDiffAt_trivializationAt_apply).
Smoothness is expressed through the total-space charts of the topological alternating bundle. The module operations use Mathlib's smooth-section API, so this carrier does not require a chosen trivialization or a global smooth alternating-bundle instance.
The fixed-coefficient section and degree-two evaluation adapters generalize the corresponding
declarations in TauCeti.Geometry.Manifold.TwoForm.Basic.
For degree two, use the ordered-pair evaluation to obtain the value in the fibre over a point.
The accompanying API provides alternation, extensionality, and C^n smoothness after applying
the form to C^n tangent fields; the fixed-coefficient section exposes the same operations in a
trivial bundle. On a Hausdorff manifold, two smooth forms agreeing on a dense set are equal
(TauCeti.SmoothBundleForm.eq_of_forall_mem_dense).
A rough bundle-valued form has C^n regularity when its graph is a C^n section of the
alternating bundle with fibres TangentSpace I x [⋀^Fin k]→L[ℝ] V x; n = ∞ gives smoothness.
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The defining characterization of IsSmoothBundleForm.
The submodule of smooth V-valued rough k-forms.
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Membership in smoothBundleForms is exactly smoothness of the corresponding section.
A smooth bundle-valued differential k-form.
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Two smooth bundle-valued forms are equal when they agree on every tangent tuple.
Two smooth bundle-valued forms on a Hausdorff manifold that agree on a dense set are equal: their sections are continuous maps into the total space of the alternating bundle, which is Hausdorff.
The smooth section underlying a smooth bundle-valued differential form.
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Reconstruct a smooth bundle-valued form from its smooth section.
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The section view and reconstruction are mutual inverses on forms.
The section view and reconstruction are mutual inverses on sections.
The section view determines a smooth bundle-valued form uniquely.
Evaluation of a smooth bundle-valued two-form on an ordered pair of tangent vectors returns the value in the fibre over the base point.
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Evaluation on two equal tangent vectors vanishes by alternation.
Swapping the inputs of a bundle-valued two-form negates its value.
Evaluation of a sum of degree-two forms is the sum of the evaluations.
Evaluation of the negative of a degree-two form is the negative of the evaluation.
Ordered-pair evaluation is additive in its first tangent argument.
Ordered-pair evaluation is additive in its second tangent argument.
Real scalar multiplication in the first tangent argument scales the fibre value.
Real scalar multiplication in the second tangent argument scales the fibre value.
Negating the first tangent vector negates the evaluation of a degree-two form.
Negating the second tangent vector negates the evaluation of a degree-two form.
Two smooth bundle-valued two-forms have the same value at a point when their ordered-pair evaluations there agree.
Two smooth bundle-valued two-forms are equal when their ordered-pair evaluations agree.
Two smooth bundle-valued two-forms are equal exactly when all ordered-pair evaluations agree.
Evaluating a smooth bundle-valued two-form on two C^n tangent fields along a C^n map is
C^n.
A fixed-coefficient rough form is C^n when it is a C^n section of the existing
alternating tangent bundle. Degree and coefficient space are inferred from the form.
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The fixed-coefficient regularity predicate is the existing section regularity predicate.
A regular fixed-coefficient form is a regular section of the alternating bundle.
Addition preserves regularity of the actual fixed-coefficient bundle sections.
The zero differential form has every section regularity.
Finite sums preserve section regularity of differential forms.
Negation preserves regularity of the actual fixed-coefficient bundle section.
Constant scalar multiplication preserves regularity of the actual bundle section.
Multiplication by a scalar C^n function preserves the regularity of a rough form.
A C^n form is C^m for every m ≤ n.
Smoothness of a form read in tangent trivializations: for a finite-dimensional model
space, a form is C^n exactly when, near each point x, its values on the frame
e.symmL y ∘ v of the tangent trivialization e at x, for each fixed tuple v of model
vectors, are C^n at x.
A smooth fixed-coefficient rough form lies in the smooth bundle-form submodule.
A smooth fixed-coefficient differential k-form.
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The underlying rough form of a smooth form is a smooth bundle section.
The section underlying a smooth form is smooth.
The underlying rough form of a smooth form is a smooth fixed-coefficient form.
Evaluating a smooth form after transporting its degree across an equality.
Evaluating the underlying rough form of a degree transport evaluates transported vectors.
Successive degree transports collapse to the transport along their composite equality.
Inverting a degree transport gives the transport along the inverse equality.
The section underlying a smooth form is differentiable.
The section underlying a smooth form is differentiable at every point.
Evaluating a smooth form on vector fields differentiable at a point gives a function differentiable at that point.
The smooth section underlying a fixed-coefficient smooth form.
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Reconstruct a fixed-coefficient smooth form from its smooth section.
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The section view and reconstruction are mutual inverses on forms.
The section view and reconstruction are mutual inverses on sections.
The section view determines a smooth fixed-coefficient form uniquely.
The rough form underlying a sum of smooth forms is the sum of their rough forms.
The rough form underlying the negation of a smooth form is the negation of its rough form.
Multiplication of smooth forms by a smooth real function, as a real-linear map.
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The rough form underlying the product of a smooth form with a smooth function is the pointwise product.
A smooth form whose degree exceeds the dimension of the model space vanishes.
The constant smooth form whose value is the alternating map A in model-space coordinates.
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The underlying rough form of const A is A transported to each tangent fibre.
Evaluating a constant smooth form transports its arguments back to the model space.
The coordinate one-form dz of the real line.
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The coordinate one-form dz of the real line sends a tangent vector to itself.
Evaluating a smooth degree-two form on two C^n tangent fields along a C^n map is C^n.
This is the trivial-bundle specialization of SmoothBundleForm.contMDiff_eval₂.
The algebraic bilinear form represented by the value of a real degree-two smooth form.
This generalizes SmoothTwoForm.bilinFormAt from
TauCeti.Geometry.Manifold.TwoForm.Basic. The view interoperates with APIs phrased in terms of
LinearMap.BilinForm, including the symplectic constructions.
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The bilinear form represented by a degree-two smooth form is alternating.
The bilinear form represented by a degree-two smooth form at a point vanishes exactly when the form vanishes there.
The value of a smooth form as a continuous alternating map on the model fibre.
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The degree-two alternating-map view evaluated on a tuple agrees with ordered-pair evaluation.