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PropositionStatement: AI-adaptedProof: AI-adaptedprecheck passaudited 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.

Satellites give the first derived functor

Statement

Assume the Axiom of Dependent Choice.

Let A and B be abelian categories, and let F:AB be additive.

If A has enough projectives, F is right exact, and S=(Sn) is any universal homological delta functor equipped with a chosen natural isomorphism S0F, then S1L1PF naturally, for every supplied projective resolution datum P on all objects of A. In this sense the first left satellite of F, defined as the degree-one term of a universal homological delta functor extending F, agrees with L1PF.

If A has enough injectives, F is left exact, and T=(Tn) is any universal cohomological delta functor equipped with a chosen natural isomorphism T0F, then T1RI1F naturally, for every supplied injective resolution datum I on all objects of A. This is the corresponding first right satellite agreement.

Facts & Assumptions

Given: A universal delta functor extending F and the corresponding derived delta functor.

[L1]

Derived functors are universal delta functors (Derived functors are universal delta functors).

[L2]

Two universal delta functors equipped with chosen degree-zero identifications to the same functor are uniquely isomorphic (Universal delta functors extending the same degree-zero functor are uniquely isomorphic).

[L3]

Universality is the structure that defines the satellite terminology used on this page (Universal delta functor).

[L4]

The derived delta functors come with canonical degree-zero identifications to F (Left derived functors form a homological delta functor, Right derived functors form a cohomological delta functor).

Proof

technique · direct
1.1

In the homological case, [L1] makes (LnPF) universal and [L4] identifies its degree-zero term canonically with F. The given satellite functor S is also a universal extension of F by [L3]. Therefore [L2] yields a unique isomorphism of delta functors SLPF, and its degree-one component is the asserted natural isomorphism S1L1PF.

L1L2L3L4givenalgebra
2.1

The cohomological case is identical with (RInF) in place of (LnPF). Its degree-one component gives the natural isomorphism T1RI1F.

L1L2L3L4step 1.1

Depends on

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