TheoremStatement: Literature-sourcedProof: AI-generatedSession-authored (Fable 5 assisted)precheck passjudge pass (gpt-5.6-terra)audited 2026-08-28‡ 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.

An equivalence between abelian categories is exact

Statement

Every equivalence between abelian categories is exact.

Facts & Assumptions

Given: An equivalence $F : A \to B$ between abelian categories.

[L1]

Equivalences preserve all limits and colimits that exist (Equivalences preserve, reflect, and create limits and colimits in the isomorphism-invariant sense).

[L2]

Abelian categories are additive (Abelian category).

[L3]

A functor between additive categories is additive exactly when it preserves finite biproducts (A functor between additive categories is additive exactly when it preserves finite biproducts).

[L4]

Exact means additive, left exact, and right exact (Left exact and right exact functors, Exact functor between abelian categories).

Proof

technique · direct

1.1

By [L1], the functor $F$ preserves finite limits and finite colimits. So by [L4] it is left exact and right exact. In particular it preserves finite products and finite coproducts.

L1L4

2.1

Since the source and target are additive by [L2], those finite products and coproducts are finite biproducts. Therefore step 1.1 lets [L3] conclude that $F$ is additive. Together with step 1.1, that is exactly the definition of exactness in [L4].

L2L3L4step 1.1∎

Depends on

Used by

Nothing in the library uses this result yet.

Dependency tree · two levels

19 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

Emily Riehl, Category Theory in Context, Lemma 3.4.5 and Definition 3.4.7 (standard reference, not scraped)