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.
Oracle Computability, the Jump, and Turing Degrees: Examples and Counterexamples
1 · Prerequisites
- Construction of the Natural Numbers
- Construction of the Real Numbers via Cauchy Sequences
- Construction of the Real Numbers via Dedekind Cuts
- Countability and Uncountability
- Decidable, Recognizable, and Enumerable Languages
- Finite Counting, Factorials and Binomial Coefficients
- Formal Languages, Encodings, and Decision Problems
- Foundations of the Real Numbers for Analysis
- Linear Recurrences and Rational Generating Functions
- Oracle Computability, the Jump, and Turing Degrees
- Relations, Functions, and Quotients
- Robust Machine Models and Universal Computation
- Sequences and Limits
- The Arithmetical Hierarchy and Post's Theorem
- The ZFC Axioms and the Basic Set Constructions
- Turing Machines, Configurations, and Computation
2 · Summary
These examples make quotienting by Turing equivalence, nonuniform oracle use, and the finite nature of a concrete oracle transcript explicit.
3 · Logical flowchart
4 · Definitions, theorems and proofs
None yet.
5 · Examples, counterexamples and false statements
Changing representatives of a degree comparison
Example
Let and . The tags can be ignored or supplied as constant bits, so and . Thus a comparison gives the same degree comparison when these particular representatives are replaced by and .
Facts & Assumptions
Given: sets and their zero-padded tagged versions.
Verification
A -oracle decides by even queries, while an -oracle decides by querying on even inputs and returning on odd inputs. Thus , and likewise .
A Turing reduction without a truth table
Example
Set . The non-domination argument guarantees at least one set which has no everywhere-total oracle functional computing it from . This is an existence example: a Turing computation may need an oracle-dependent amount of information before it knows its answer.
Facts & Assumptions
Given: .
Verification
By Truth-table reduction, that failure says no functional computing from is total on every possible oracle.
A finite oracle-query transcript
Statement refuted
A computation deciding whether belongs to its oracle must read every bit of that oracle.
Counterexample
Given: an oracle .
The machine that queries only and returns the answer decides this predicate for every oracle . Its transcript has the single query .
Any two oracles agreeing at give exactly the same run and output, even if they differ elsewhere. This finite witness refutes the claimed whole-oracle read.