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

1.1F2A1given

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 Cα⊆Aα. This defines the whole ladder sequence from the fixed parameters.

1.2F1F3F4F5A1given

Let X⊆ω1 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=acc⁡ω1(X) club. Let S={α:X∩α=Aα}, stationary by F1. For any club D, F4 makes D∩E club, so it meets S. Thus S∩E is stationary.

2.1F2step 1.1step 1.2∎

If α∈S∩E, then α is a nonzero limit and Aα=X∩α is cofinal in α. The first alternative of step 1.1 therefore applies, giving Cα⊆Aα⊆X. Hence the containment-guess set contains the stationary set S∩E and itself meets every club. This is exactly F2's club principle.

Depends on

Used by

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