Alphabeta Math
TheoremStatement: Literature-sourcedProof: AI-adaptedPipeline-generatedprecheck passjudge pass (gpt-5.6-terra)audited 2026-09-06‡ 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.

Global dimension is the supremum of nonzero Ext degrees

Statement

For an abelian category with enough projectives, gldim⁡A=sup⁡{n:Ext⁡n(M,N)≠0 for some M,N}; the supremum is taken in N0∪{∞}, with sup⁡∅=0. If A also has enough injectives, the dual supremum of injective dimensions has the same value.

Facts & Assumptions

Given: The stated enough-projectives or enough-injectives hypothesis.

Proof

technique · direct
1.1

By Global dimension of an abelian category, global dimension is the supremum of projective dimensions. Projective dimension at most n iff higher Ext vanishes says that each individual projective dimension is exactly the least uniform Ext-vanishing bound.

givenconstruct
2.1

Taking suprema over objects gives the displayed equality. If there is no nonzero object, both sides are 0 by the stated convention; otherwise Ext⁡0(M,M) contains 1M≠0 for every nonzero M, so the degree-zero endpoint is present. When there are also enough injectives, Injective dimension at most n iff higher Ext vanishes gives the same uniform Ext bounds and hence the dual formulation.

step 1.1algebra∎

Depends on

Used by

Nothing in the library uses this result yet.

Dependency tree · two levels

13 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