OpenAI reports real-sentence decision in the counting hierarchy

The truth of existential–universal sentences over the reals is decidable in one fixed level of the counting hierarchy, even when their integer polynomials are specified by arithmetic circuits; in particular, the existential theory of the reals lies in the counting hierarchy.

Sources for this record

What was already known

Canny and Renegar gave polynomial-space decision bounds for the existential fragment and fixed real-quantifier-block languages. The manuscript places the two-block circuit-encoded language in the smaller counting hierarchy.

AI involvement AI-led

OpenAI credits itself as manuscript author and states that its internal frontier model produced the results in this release. Individual human input is not detailed enough to establish task-only autonomy.

OpenAI is named as author on the manuscript, and its release attributes the results to an internal frontier model. The individual human input is not detailed enough to establish autonomy.

Importance Major

Improves the known complexity upper bound for existential and existential–universal real sentences.

Limitations

The number and order of real quantifier blocks are fixed to existential–universal; this does not place the unrestricted full first-order theory of reals in the counting hierarchy. No completed proof check was documented in the available sources.

Technical verification Reported

Reported is the default when evidence for a higher level is insufficient. The OpenAI-authored manuscript reports and argues the result, but the reviewed sources do not document a completed check of the full assessed claim.

Human understanding Few

Few is the default when evidence for a higher level is insufficient. No named person is documented as explaining the central argument for this assessed contribution.

Correction and publication history

2026-10-18 · publication

Primary manuscript, attribution, and prior-work review for non-notifying local inclusion; technical check remains undocumented.

Read this published revision