Alphabeta Math
LemmaStatement: Literature-sourcedProof: AI-adaptedPipeline-generatedprecheck passverified 2026-09-23 (gpt-6-sol)
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.
  • AI-generated: a genuinely novel statement formulated by AI, with no source for the claim itself.

These labels describe origin, not correctness: citations and verification chips remain separate evidence.

Sphere and ball measures scale in Rn

Statement

Assume the Axiom of Countable Choice. For n≥1 and r>0, ∣∂Br∣=ωn−1rn−1 and ∣Br∣=ωn−1rn/n; both factors are finite and positive.

Proof

Given: Countable Choice, n≥1, and r>0.

1.1

The parametrization θ↦rθ gives ∣∂Br∣=ωn−1rn−1 [given].

2.1

Under Countable Choice, applying Polar coordinates decompose Lebesgue measure into r^{n-1} dr d sigma to 1Br gives ∣Br∣=ωn−1∫0rtn−1dt=ωn−1rn/n [given, algebra]. ∎

Depends on

Used by

…and 2 more results.

Dependency tree · two levels

17 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