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.
Five-term sequence of a composite functor
Example
For a fixed extension , the composite-invariants five-term sequence is For , and trivial coefficients , it becomes . Thus even this specialization illustrates that the last term is not required to be the image of the preceding arrow.
Facts & Assumptions
Given: The LHS supplied-data and DC or supplied-comparison convention.
The composite five-term sequence has terms , , , and (Five-term exact sequence of the Grothendieck spectral sequence).
For invariants these maps are inflation, restriction and transgression, with their resolution descriptions (Five-term exact sequence from LHS).
Group cohomology is Ext of the trivial group-ring module, computable from a supplied projective resolution by balance (Group cohomology as a derived functor, Projective and injective constructions of Ext agree for supplied resolutions).
Verification
Substitute and into F1. The five terms become, in order, , , , and . F2 identifies the first and last maps with its bottom-cycle inflation, the second with restriction of invariant cocycles, and the middle with from to . Hence every term and arrow agrees with F2, without importing a later cocycle-classification theorem.
To compute the specialization let . Its trivial -module has the free resolution with augmentation and alternating differentials , , , continuing periodically. Indeed for , the kernel of is and the kernel of is ; these are the preceding images. The augmentation kernel is also . Rank-one free terms are projective by lifting the image of their generator. Hom into trivial has successive differentials . Thus F3 gives and .
For , invariants are identity and the positive cohomology is zero by exactness of any supplied resolution. Consequently step 1.1 has four zero non-initial terms before its final , as claimed. All maps in that displayed finite portion are zero, its transgression is zero and exactness holds at every required position. There is no final surjectivity. The rank-one periodic calculation itself is choice-free; only the common resolution-independent comparison convention is inherited.
Depends on
- Five-term exact sequence of the Grothendieck spectral sequence
- Five-term exact sequence from LHS
- Group cohomology as a derived functor
- Projective and injective constructions of Ext agree for supplied resolutions
- The axiom of dependent choice: a relation in which every element is related to something admits an $\mathbb{N}$-indexed chain
Used by
Nothing in the library uses this result yet.
Dependency tree · two levels
26 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
- Weibel, 6.8.3 (standard reference, not scraped)