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.
Induction on well-founded setlike relations
Statement
Let be well-founded and setlike on a definable class . If a definable property is progressive, meaning that for every , , then holds for all . Set parameters in are allowed. This holds without Foundation.
Facts & Assumptions
Given: Work in ZF unless the statement explicitly weakens or supplements it; fix the objects and hypotheses of the statement.
For every setlike relation on a definable class and , there is a least predecessor-closed set containing . It consists exactly of nodes reachable from by a finite sequence of predecessor steps. Well-foundedness is not needed. (Finite predecessor closures are sets)
Proof
If there is a counterexample , take its predecessor-closed set and separate the nonempty set . Well-foundedness gives a minimal .
Every predecessor of belongs to , and none belongs to by minimality. Hence all satisfy . Progressiveness gives , contrary to . Therefore no counterexample exists.
Depends on
Used by
Dependency tree · two levels
3 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
- Marks, Set Theory, Berkeley edition — Lemma 6.2 and Theorem 6.5 p.30. (standard reference, not scraped)