Polynomial hitting lists for noncommutative rational formulas

For noncommutative rational formulas over Q with unrestricted inverse nesting, can a deterministic polynomial-time algorithm produce a polynomial-size list of matrix evaluations hitting every nonzero formula of bounded size?

Why it matters and what counts as progress

Why it matters: Polynomial lists would improve the quasipolynomial black-box bounds known for this rational-formula model.

What counts as progress: A list with polynomial dimension and total bit length on which each admissible nonzero formula has at least one defined invertible evaluation.

How the problem developed

  1. 4 May 2022 · Partial result [1]

    Vikraman Arvind, Abhranil Chatterjee and Partha Mukhopadhyay Constructed deterministic quasipolynomial-time hitting sets for rational formulas of inversion height two, the first nested-inverse case.

  2. 2024 · Partial result [2]

    Vikraman Arvind, Abhranil Chatterjee and Partha Mukhopadhyay Reported quasipolynomial-size black-box hitting sets for rational formulas of arbitrary inversion height.

  3. 24 Sept 2026 · Proof claim [3]

    OpenAI Released a manuscript claiming deterministic polynomial-time construction of polynomial-size rational-matrix hitting lists for admissible nonzero noncommutative rational formulas.

AI contribution

Polynomial Hitting Lists for Noncommutative Rational Formulas

OpenAI

Given unary n and a size bound s, a deterministic machine constructs in polynomial bit time a polynomial-size list of rational matrix tuples of polynomial total output length and common polynomial dimension. Every admissible nonzero noncommutative rational formula over Q of size at most s has a defined, invertible evaluation on a listed tuple.

AI involvementAI-led
ImportanceNotable
Technical verificationFormal (Lean 4 with Mathlib)
Human understandingFew
Reported

Sources

  1. Arvind, Chatterjee and Mukhopadhyay, Black-Box Identity Testing of Noncommutative Rational Formulas of Inversion Height Two in Deterministic Quasipolynomial Time
  2. Arvind, Chatterjee and Mukhopadhyay, Black-Box Identity Testing of Noncommutative Rational Formulas in Deterministic Quasipolynomial Time
  3. OpenAI, Polynomial Hitting Lists for Rational Formulas
  4. Polynomial Hitting Lists for Noncommutative Rational Formulas
  5. Rational hitting-list formalization scope
  6. Lean rational hitting-list theorem
Website timeline

Publication dates and editorial changes.