Alphabeta Math
DefinitionDefinition: Literature-sourcedProof: Not applicableSession-authored (Fable 5 assisted)audited 2026-08-11
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.

Faithful, full, fully faithful, essentially surjective, and split essentially surjective functors

Definition

Let F:CDF:\mathcal C\to\mathcal D be a functor (Covariant functor, identity functor, composite functor, and contravariant functor). For each A,BA,B, it induces

FA,B:C(A,B)D(FA,FB),fFf.F_{A,B}:\mathcal C(A,B)\to\mathcal D(FA,FB),\qquad f\mapsto Ff.

The functor is faithful when every FA,BF_{A,B} is injective, full when every FA,BF_{A,B} is surjective, and fully faithful when every FA,BF_{A,B} is bijective (Injection, surjection, bijection).

It is essentially surjective when every object DD of D\mathcal D is isomorphic to some FCFC (Isomorphism, groupoid, and connected category). It is split essentially surjective when the data include, for every DD, a specified object CDC_D and specified isomorphism εD:FCDD\varepsilon_D:FC_D\to D. The word split records these witnesses and is strictly stronger as data than their mere existence.

Depends on

Used by

Dependency tree · next 3 levels

Direct dependencies and their dependencies through the next three levels: 15 results over 7 levels. An arrow runs from a result to what uses it, and this result sits at the bottom with a heavier outline. Click the chart to enlarge it.

Sources