CorollaryStatement: AI-adaptedProof: AI-generatedprecheck passjudge pass (gpt-5.6-terra)audited 2026-09-05‡ 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.

The derived long exact sequence

Statement

Assume the Axiom of Dependent Choice.

Let $A$ and $B$ be abelian categories, let $P$ be supplied projective resolution data on all objects of $A$ , and let $I$ be supplied injective resolution data on all objects of $A$ .

If $F : A \to B$ is additive and right exact, then every short exact sequence $0 \to A^{'} \to A \to A^{''} \to 0$ in $A$ yields a natural long exact sequence $\dots \to L_{n}^{P} F (A^{'}) \to L_{n}^{P} F (A) \to L_{n}^{P} F (A^{''}) \to L_{n - 1}^{P} F (A^{'}) \to \dots \to L_{0}^{P} F (A^{''}) \to 0.$

If $G : A \to B$ is additive and left exact, then every such short exact sequence yields a natural long exact sequence $0 \to R_{I}^{0} G (A^{'}) \to R_{I}^{0} G (A) \to R_{I}^{0} G (A^{''}) \to R_{I}^{1} G (A^{'}) \to R_{I}^{1} G (A) \to \dots .$

Facts & Assumptions

Given: A short exact sequence $0 \to A^{'} \to A \to A^{''} \to 0$ in $A$ .

[L1]

Left derived functors form a homological delta functor (Left derived functors form a homological delta functor).

[L2]

Right derived functors form a cohomological delta functor (Right derived functors form a cohomological delta functor).

Proof

technique · direct

1.1

The first displayed sequence is exactly the long exact sequence attached by [L1] to the given short exact sequence.

L1given

2.1

The second displayed sequence is exactly the long exact sequence attached by [L2] to the same short exact sequence.

L2step 1.1∎

Depends on

Used by

Nothing in the library uses this result yet.

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

Charles A. Weibel, An Introduction to Homological Algebra, Chapter 2 `Derived Functors` (standard reference, not scraped)