Alphabeta Math
CounterexampleConstruction: AI-generatedVerification: AI-generatedprecheck passjudge pass (gpt-5.6-terra)audited 2026-09-12
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.

One accepting branch is enough for an NFA to accept

Statement refuted

The statement "an NFA accepts a word only if every branch accepts" is false.

Facts & Assumptions

Given: The NFA and input word abb from FALSE: an NFA accepts only if every branch accepts.

[A1]

The statement refuted is: an NFA accepts a word only if every branch accepts.

[L1]

The false statement's refutation already exhibits one accepting branch and one rejecting branch on the same input, by FALSE: an NFA accepts only if every branch accepts.

Counterexample

technique · direct
1.1L1given

On the input abb, one branch follows the path q0→aq1→bq2→bq3 and accepts, while another branch stays on the start-state loop too long and rejects.

2.1step 1.1

Therefore the same machine and the same word witness that acceptance can occur even when not every branch accepts.

3.1A1step 2.1∎

This contradicts [A1], so the displayed NFA on abb is a counterexample.

Depends on

Used by

Nothing in the library uses this result yet.

Dependency tree · two levels

2 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