Alphabeta Math
ExampleConstruction: AI-generatedVerification: AI-generatedprecheck passaudited 2026-09-01‡ rests on unproved material (inherited)
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.

‡ Rests on 3 statements not proved in this library, by way of the results it cites. This item cites no such statement directly; it depends on results that do. The unproved premises it inherits are ‡ Cohen's first model: an infinite Dedekind-finite set of reals, ‡ Sierpiński 1947: the generalised continuum hypothesis implies the Axiom of Choice and ‡ The continuum hypothesis and its generalisation are independent of ZFC. Each is recorded with a citation to the literature and is not established here, because the track that would prove it has not yet been developed in this library. Everything else in this proof is proved here.

Schanuel's lemma for two presentations of a module

Example

For Z/2Z, compare the two short exact sequences 0→2Z→Z→Z/2Z→0 and 0→2Z⊕Z→Z⊕Z→Z/2Z→0, where the second surjection sends (a,b) to aˉ. Schanuel's lemma predicts 2Z⊕(Z⊕Z)≅(2Z⊕Z)⊕Z.

Facts & Assumptions

Given: The two displayed short exact sequences.

[L1]

Schanuel's lemma gives a stable isomorphism between the two kernels (Schanuel's lemma in an abelian category).

[L2]

Short exact sequences of modules are exact module-theoretic rows (Exact sequences and short exact sequences of modules).

Verification

technique · direct
1.1

The kernel of Z→Z/2Z is 2Z, and the kernel of (a,b)↦aˉ is 2Z⊕Z. Thus the two displayed rows are short exact in the sense of [L2].

L2givenalgebra
2.1

Since 2Z≅Z, both sides of Schanuel's conclusion are free abelian groups of rank three. Hence they are isomorphic, exactly as [L1] predicts.

L1step 1.1algebra∎

Depends on

Used by

Nothing in the library uses this result yet.

Dependency tree · two levels

8 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