Generalized Star Height at Most Three

OpenAI

Every regular language over a finite alphabet has a generalized regular expression over that same alphabet with at most three nested Kleene stars, allowing union, concatenation and complement.

Sources for this record

What was already known

The generalized star-height problem asked whether one finite bound works for every regular language. This manuscript improves earlier bounds of thirteen and four from the same research series.

AI involvement AI-led

OpenAI credits an internal model with the manuscript and proof artifacts. No separate human construction or item-specific autonomous session is documented.

OpenAI credits an internal model with producing the manuscripts and proof artifacts; the record does not establish little or no human mathematical input for this particular result.

Importance Major

A universal bound of three would settle the uniform-boundedness question.

Limitations

The theorem bounds nesting depth, not expression size or construction time. It does not determine whether height one suffices or the exact maximum.

Technical verification Formal (Lean 4)

The public Lean main theorem proves HasHeightAtMost L 3 for every regular language over a finite alphabet. The scope note identifies same-alphabet expressions and same-free-monoid complements; the comparator file contains a placeholder challenge and is not itself the completed proof. The completed Lean theorem supports the Formal rating.

Formal checking

Lean proof term for the selected statement, with source-reported formalization

Checker
OpenAI Lean formalization
Scope
Every regular language over a finite alphabet has generalized star height at most three
Basis
Reported by the linked checker
Evidence source

Checking a formal statement does not establish that it matches the original problem.

Human understanding Few

The available release provides no named human explanation of the central construction. Few is the evidence default.

Correction and publication history