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 Cohen reals form a symmetric set but their enumeration is not symmetric
Statement
The coordinate action is . Each has support , has empty support, and is forced infinite with distinct members. The canonical enumeration has no finite support, and no enumeration of belongs to the symmetric model.
Facts & Assumptions
Given: The hypotheses, objects, and conventions in the Statement.
The basic Cohen symmetric system gives and .
Symmetry lemma for forcing automorphisms transports forced assertions.
Proof
F1 shows that supports and supports ; their subnames are checks, so both are HS. For , below any condition choose a fresh bit coordinate and set opposite bits at . Hence the set forcing is dense. Every finite collection is therefore forced to have its displayed size, so is infinite.
Let be the canonical graph . Given finite , choose and . Their transposition fixes but sends the graph value at from to , so it does not fix . Thus no finite supports that name.
Now let be onto and let the finite set support and contain the first-coordinate support of . Choose . Since forces surjectivity, some and satisfy . Choose outside and outside the first-coordinate support of , and let swap . Then , , and F2 gives
Because the -coordinate is absent from , and agree on their common domain and have a common extension. That extension forces , contrary to step 1.1. Therefore no HS name can enumerate .
Depends on
Used by
Dependency tree · two levels
9 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
- Karagila, Forcing & Symmetric Extensions, Propositions 10.22–10.24 (standard reference, not scraped)