Alphabeta Math
PropositionStatement: AI-adaptedProof: AI-adaptedPipeline-generatedjudge pass (gpt-5.6-terra)audited 2026-09-09
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.

Diamond implies clubsuit

Statement

In ZFC, implies .

Facts & Assumptions

Given: A diamond sequence (Aα)α<ω1; assume AC.

[F1]

Every subset of ω1 is guessed stationarily often. Diamond on ω1

[F2]

The club principle and the explicit thinning of cofinal sets to order-type-ω ladders are as defined here. The Ostaszewski club principle

[F3]

The limit points of an unbounded subset of an ordinal of uncountable cofinality form a club. Limit points of an unbounded set form a club

[F4]

A finite intersection of clubs of uncountable cofinality is club. Intersections of fewer than the cofinality many clubs

[A1]

Proof

1.1

Fix the ordinal enumerations in F2 using A1. At a nonzero countable limit α, if Aα is cofinal in α, apply the explicit minimum recursion in F2 to it and call its range Cα. Otherwise apply the same recursion to α itself. In both situations Cα is cofinal of order type ω; when Aα is cofinal we also have CαAα. This defines the whole ladder sequence from the fixed parameters.

F2A1given
1.2

Let Xω1 be uncountable. It is unbounded, since a bounded subset lies inside a countable ordinal and is countable. F5 and A1 give cf(ω1)=ω1>ω, so F3 makes E=accω1(X) club. Let S={α:Xα=Aα}, stationary by F1. For any club D, F4 makes DE club, so it meets S. Thus SE is stationary.

F1F3F4F5A1given
2.1

If αSE, then α is a nonzero limit and Aα=Xα is cofinal in α. The first alternative of step 1.1 therefore applies, giving CαAαX. Hence the containment-guess set contains the stationary set SE and itself meets every club. This is exactly F2's club principle.

F2step 1.1step 1.2

Depends on

Used by

Nothing in the library uses this result yet.

Dependency tree · two levels

24 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