DefinitionDefinition: Literature-sourcedProof: Not applicablejudge pass (gpt-5.6-terra)audited 2026-08-30

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.

Zero complex and stalk complex

Definition

Fix a zero object $0$ of an abelian category (Initial object, terminal object, and zero object).

The zero complex is the chain complex with $C_{n} = 0$ for every $n$ and every differential equal to the zero endomorphism of $0$ .

For an object $A$ and an integer $n$ , the stalk complex $S^{n} (A)$ is the chain complex with $S^{n} (A)_{k} = {\begin{cases} A, & k = n, \\ 0, & k \neq n, \end{cases}$ and every differential zero. It is concentrated in degree $n$ .

Depends on

Used by

A zero-differential complex has homology equal to each term Example

Dependency tree · two levels

5 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, Chapter 1 of An Introduction to Homological Algebra (standard reference, not scraped)
The Stacks Project, Section 12.13: Complexes (standard reference, not scraped)