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.
Halting on every input is not recognizable
Statement
Let Then is not recognizable.
Facts & Assumptions
Given: The totality language .
The complement of is not recognizable, by The complement of the halting problem is not recognizable.
The chosen machine encoding is effective, so from a code one can effectively build a new coded machine whose finite control contains and , by A fixed effective binary encoding of deterministic one-tape Turing machines.
Recognizability means acceptance by some deterministic Turing machine on exactly the language members, by Decidable and recognizable languages.
is the language of coded pairs on which the decoded machine halts on the decoded input, by The halting problem .
Proof
Given an input for the complement of from [L4], effectively build a machine with input alphabet as follows. On input , the machine simulates on for exactly steps. If the simulation has not halted by then, halts and accepts. If the simulation has halted within those steps, then enters an infinite loop. This construction is effective by [L2].
If never halts on , then every finite step-bounded simulation in step 1.1 remains nonhalting, so halts on every input . Conversely, if halts on after exactly steps, then for every input with the machine detects that halting event during its first simulated steps and therefore loops forever. Hence .
Suppose for contradiction that were recognizable. Then, on input , one could compute and run the assumed recognizer for on that code. By step 2.1, this would recognize the complement of , contradicting [L1]. Therefore is not recognizable, by [L3].
Depends on
Used by
Nothing in the library uses this result yet.
Dependency tree · two levels
13 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
- Stan Nelson, Computability: Undecidable Problems (standard reference, not scraped)