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.
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- 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.
Knot genus is invariant under mirroring and reversal
Statement
Assume the Axiom of Countable Choice. Let be a smooth oriented knot in , and let be an orientation-reversing reflection. Give the image orientation, and let denote reversal of the knot orientation. Then .
Statement references
Facts & Assumptions
Given: AC, a smooth oriented knot , and a smooth reflection of .
Knot genus is the minimum genus among connected compact smooth oriented surfaces whose oriented boundary is the knot. (Seifert surfaces and smooth knot genus)
For a connected compact orientable surface with one boundary component, reversing its orientation or applying a diffeomorphism preserves its genus. (Finite surface normal forms, Jordan disks, and torsion control)
AC is the sequence-choice principle. (The Axiom of Countable Choice ())
Proof
Given: The knot , reflection , and AC.
If is any spanning surface for , its image is a connected compact smooth surface with boundary . Push the orientation of forward to orient ; reversing the boundary orientation instead is achieved by reversing the orientation on . By [F2], all these surfaces have genus . Thus every genus admissible for is admissible with the same value for and .
Apply the same argument using and orientation reversal again. This gives the reverse inclusion of the sets of admissible genera, so their minima agree for all four knots.
Depends on
Used by
Dependency tree · two levels
32 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
- Burde and Zieschang, Knots, 2nd revised and extended edition (standard reference, not scraped)