Source authenticated

Lichter and Schweitzer's question: does witnessed symmetric choice strictly increase the expressive power of CPT with counting?

Theorem 1.1: over a vocabulary of eight binary relations there is a CPT+WSC sentence with a single WSC operator that returns a Boolean value on every finite structure and whose true-model class is not defined by any CPT sentence, even with counting and unbounded set rank; so CPT+WSC is strictly more expressive than CPT in Lichter and Schweitzer's sense. Not shown: whether CPT+WSC captures polynomial time, or the effect of nested WSC operators, both of which the paper leaves open.

Exact FrontierDelta

Prior state unknown→proved

Scope and record

Occurred: Sep 24, 2026

Delta type: SOURCE CLAIM

Assumptions: VibeMathed verification: lean-checked. Publication: announcement. AI contribution: ai-discovered. VibeMathed editorial classifications, scores, notes, relations, and dataset structure are CC BY 4.0. Source statements and linked content retain their own rights.

Canonical aliases: Lichter and Schweitzer's question: does witnessed symmetric choice strictly increase the expressive power of CPT with counting? · Witnessed symmetric choice beats CPT

Confidence: Not scored

Registry verification: lean checked · announcement · candidate

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Attribution

VibeMathed
registry · event recorded by

Unreleased internal OpenAI model
model · ai model contributor · OpenAI

Artifacts and verifiers

Lean statement: WitnessedChoice.lean (comparator challenge)

lean artifact · pending

Artifact ↗
Lean solution module OAI/Computability/WitnessedChoice/Main.lean

lean artifact · pending

Artifact ↗

Compute record

No linked compute attempts recorded.

Lineage and corrections

Lichter and Schweitzer's question: does witnessed symmetric choice strictly increase the expressive power of CPT with counting? parent of this event

This event attributed to Unreleased internal OpenAI model

Lichter and Schweitzer's question: does witnessed symmetric choice strictly increase the expressive power of CPT with counting? evidence for this event

Lean solution module OAI/Computability/WitnessedChoice/Main.lean evidence for this event

VibeMathed record: Lichter and Schweitzer's question: does witnessed symmetric choice strictly increase the expressive power of CPT with counting? evidence for this event

Lichter and Schweitzer, Choiceless Polynomial Time with Witnessed Symmetric Choice (arXiv 2205.14003) evidence for this event

Theorem 1.1: over a vocabulary of eight binary relations there is a CPT+WSC sentence with a single WSC operator that returns a Boolean value on every finite structure and whose true-model class is not defined by any CPT sentence, even with counting and unbounded set rank; so CPT+WSC is strictly more expressive than CPT in Lichter and Schweitzer's sense. Not shown: whether CPT+WSC captures polynomial time, or the effect of nested WSC operators, both of which the paper leaves open. parent of this event

Lean statement: WitnessedChoice.lean (comparator challenge) evidence for this event

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