How statement and proof provenance work
The first chip identifies the source of the statement or construction; the second identifies the source of its local proof or verification.
- Literature-sourced: the exact statement appears in a cited source; only wording and notation differ.
- AI-adapted: a semantically identical restatement of literature-sourced material, modulo indexing, notation, and boundary cases adopted by the library.
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These labels describe origin, not correctness: citations and verification chips remain separate evidence.
The angular form generates the first de rham cohomology of the circle
Example
Under countable choice, has period one and its class generates .
Facts & Assumptions
Given: Assume countable choice. The counterclockwise oriented unit circle and the displayed one-form.
De rham cohomology of spheres: Assume countable choice. For , is in degrees and zero otherwise. For it is in degree zero and zero otherwise.
A nonzero period obstructs exactness and bounding: Let be an oriented compact boundaryless embedded -submanifold, , and let be a closed smooth -form on . If , then is not exact on , and cannot be the induced oriented boundary of a compact embedded -submanifold of .
Verification
The form is smooth and closed because two-forms on a one-manifold vanish. For , , substitution gives , hence .
The circle is compact, oriented, boundaryless and embedded, and the form is closed, so its nonzero period obstructs exactness. Since the sphere theorem gives , this nonzero class is a basis.
Source locator
Lee, angular form (17.1), p.441, and Theorem 17.21, pp.450–451; the period is calculated explicitly.
Depends on
Used by
Nothing in the library uses this result yet.
Dependency tree · two levels
15 results within two dependency steps of this one, each drawn at its shortest distance from it. An arrow runs from a result to what uses it, so the chart reads left to right and ends at this result, which carries a heavier outline. Every node is a link to that result. Click elsewhere on the chart to enlarge it.
Sources
- Nigel Hitchin, Differentiable Manifolds (2014) (standard reference, not scraped)
- John M. Lee, Introduction to Smooth Manifolds, second edition (standard reference, not scraped)