Alphabeta Math
TheoremStatement: Literature-sourcedProof: AI-adaptedPipeline-generatedjudge pass (gpt-5.6-terra)audited 2026-09-14
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.

The basic Cohen set has no countably infinite subset

Statement

Every map from ω into A in the basic Cohen model has finite range; therefore no injection ω→A, no countably infinite subset, and no enumeration of A exists.

Facts & Assumptions

Given: The hypotheses, objects, and conventions in the Statement.

[F1]

The Cohen reals form a symmetric set but their enumeration is not symmetric states the exact coordinate action πa˙n=a˙πn, pairwise distinctness, and infinitude of A.

[F2]

Symmetry lemma for forcing automorphisms transports decisions under swaps.

Proof

1.1F1F2

Let p⊩f˙:ωˇ→A˙, and enlarge a finite support E of f˙ to support p. If some q≤p forces f˙(i)=a˙n with n∉E, choose m outside E∪{n} and outside the first-coordinate support of q. Let π swap n,m. Then πf˙=f˙, πp=p, and F2 gives πq⊩f˙(i)=a˙m.

2.1F1step 1.1

The conditions q and πq agree wherever both are defined: the m coordinate was fresh and all other moved coordinates are fixed. Their union is a common extension forcing a˙n=a˙m, contradicting F1. Hence no extension of p can put a value outside {an:n∈E}, and density of decisions yields p⊩ran⁡f˙⊆{a˙n:n∈E}.

3.1step 2.1∎

Thus every such map has finite range, so none is injective or enumerates the infinite set A. A countably infinite subset would, by its meaning in ZF, carry a bijection from ω and hence an injection into A, also impossible. Fresh indices were chosen only from explicit complements of finite sets; no AC is used.

Depends on

Used by

Dependency tree · two levels

7 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