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Lean statement

Directional zero–one law under strict ellipticity

Lean is a language for mathematical statements and proofs that a computer can verify. This page shows one statement file from OpenAI’s release, possible paper matches and independent reports. The code-like names below identify the definitions or theorems selected by the proof-verification settings.

Theorem selected for verification: OAI.DirectionalZeroOne.directional_zero_one

Lean statement file: DirectionalWalk.leanShow on the mapOpenAI’s Lean catalogue does not list this as a main result; the release’s Lean notes for family 220 link it.

The Lean statement

The lines of the Lean statement that state the theorem, then the definitions in the file that it uses.

theorem directional_zero_one (d : ℕ) (hd : 3 ≤ d)    (μ : Measure (Row d)) [IsProbabilityMeasure μ]    (hell : StrictEllipticity μ) (ℓ : Fin d → ℝ) (hℓ : ℓ ≠ 0) :    annealed μ 0 (escape ℓ) = 0 ∨ annealed μ 0 (escape ℓ) = 1 := by sorry

A Lean statement states the theorem and leaves its proof as sorry on purpose. OpenAI’s proof is in a separate solution module, and a program called Comparator checks that proof against this statement.

Definitions needed to read it

Local definitions the statement names, followed through the definitions they name in turn. The match is by name in the source text, so a name reached only through notation can be missed; the full file is below.

  • abbreviation OAI.DirectionalZeroOne.Site line 10

    abbrev Site (d : ℕ) := Fin d → ℤ
  • abbreviation OAI.DirectionalZeroOne.Step line 11

    abbrev Step (d : ℕ) := Fin d × Bool
  • definition OAI.DirectionalZeroOne.stepVector line 13

    def stepVector {d : ℕ} (e : Step d) : Site d :=  fun i => if i = e.1 then (if e.2 then 1 else -1) else 0
  • definition OAI.DirectionalZeroOne.Row line 16

    def Row (d : ℕ) :=  {p : Step d → ℝ // (∀ e, p e ∈ Set.Icc (0 : ℝ) 1) ∧ ∑ e, p e = 1}
  • abbreviation OAI.DirectionalZeroOne.Environment line 23

    abbrev Environment (d : ℕ) := Site d → Row d
  • abbreviation OAI.DirectionalZeroOne.Path line 24

    abbrev Path (d : ℕ) := ℕ → Site d
  • abbreviation OAI.DirectionalZeroOne.State line 25

    abbrev State (d : ℕ) := Environment d × Site d
  • definition OAI.DirectionalZeroOne.StrictEllipticity line 27

    def StrictEllipticity {d : ℕ} (μ : Measure (Row d)) : Prop :=  ∀ᵐ p ∂μ, ∀ e, 0 < p.val e
  • definition OAI.DirectionalZeroOne.environmentLaw line 30

    noncomputable def environmentLaw {d : ℕ} (μ : Measure (Row d))    [IsProbabilityMeasure μ] : Measure (Environment d) :=  Measure.infinitePi (fun _ => μ)
  • definition OAI.DirectionalZeroOne.transition line 34

    noncomputable def transition (d : ℕ) : Kernel (State d) (State d) where
    Show the remaining 15 lines
      toFun s := ∑ e : Step d,    ENNReal.ofReal ((s.1 s.2).val e) • Measure.dirac (s.1, s.2 + stepVector e)  measurable' := by    apply measurable_from_prod_countable_left    intro x    apply Finset.measurable_sum    intro e he    apply Measure.measurable_of_measurable_coe    intro t ht    simp only [Measure.smul_apply, smul_eq_mul]    apply Measurable.mul    · exact (measurable_pi_apply e |>.comp        (measurable_subtype_coe.comp (measurable_pi_apply x))).ennreal_ofReal    · exact (Measure.measurable_coe ht).comp        (Measure.measurable_dirac.comp (measurable_id.prodMk measurable_const))
  • definition OAI.DirectionalZeroOne.historyKernel line 64

    noncomputable def historyKernel (d n : ℕ) :    Kernel ((i : Finset.Iic n) → State d) (State d) :=  (transition d).comap (fun h => h ⟨n, Finset.mem_Iic.mpr le_rfl⟩)    (measurable_pi_apply _)
  • definition OAI.DirectionalZeroOne.initialLaw line 73

    noncomputable def initialLaw {d : ℕ} (μ : Measure (Row d))    [IsProbabilityMeasure μ] (x : Site d) : Measure (State d) :=  (environmentLaw μ).map (fun ω => (ω, x))
  • definition OAI.DirectionalZeroOne.annealed line 77

    noncomputable def annealed {d : ℕ} (μ : Measure (Row d))    [IsProbabilityMeasure μ] (x : Site d) : Measure (Path d) :=  (Kernel.trajMeasure (X := fun _ => State d) (initialLaw μ x) (historyKernel d)).map    (fun z n => (z n).2)
  • definition OAI.DirectionalZeroOne.escape line 82

    def escape {d : ℕ} (ℓ : Fin d → ℝ) : Set (Path d) :=  {X | Tendsto (fun n => ∑ i, (X n i : ℝ) * ℓ i) atTop atTop}

Possible paper match, with no recorded review

Atlas selected this possible match by comparing words in the Lean statement with every statement in the family. No review of whether the statements mean the same thing is recorded.

Words of the Lean statement, its names split into words, that also appear in the theorem: ellipticity, transition, rows, eq and law. Found in the paper’s title, which its main theorem states: strict, one, zero and directional. Shared only with the release’s name for the Lean statement or OpenAI’s note on it: distributed, identically, nearest, neighbor and independent.

Statements in A directional zero–one law under strict ellipticity come first because the release’s name for this Lean statement shares words with that paper’s title.

Theorem 1.1 of A directional zero–one law under strict ellipticity

Theorem

Let d\ge3, let \PP be an independent and identically distributed law of nearest-neighbor transition rows on \ZZ^d satisfying (eq:ellipticity), and let \ell\in\RR^d\setminus\{0\}. Then

P_0(A_\ell)\in\{0,1\}.
Section 1, Introduction Read it in the paper TeX source, line 61
Show the TeX
Let $d\ge3$, let $\PP$ be an independent and identically distributed
law of nearest-neighbor transition rows on $\ZZ^d$ satisfying
\eqref{eq:ellipticity}, and let $\ell\in\RR^d\setminus\{0\}$.
Then
\[
 P_0(A_\ell)\in\{0,1\}.
\]

Other possible paper matches, closest wording first

  • Theorem 1.1 of Directional transience implies ballisticity. Words of the Lean statement, its names split into words, that also appear in the theorem: vector, ellipticity, transition, rows, real, directional and two more. Shared only with the release’s name for the Lean statement or OpenAI’s note on it: nearest, neighbor, uniform, walk and direction.
  • Proposition 3.1 of A directional zero–one law under strict ellipticity. Words of the Lean statement, its names split into words, that also appear in the theorem: initial, transition, rows, site, environment and law. Shared only with the release’s name for the Lean statement or OpenAI’s note on it: strictly and positive.
  • Corollary 1.2 of Directional transience implies ballisticity. Words of the Lean statement, its names split into words, that also appear in the theorem: annealed, vector, ellipticity, transition, rows, real and three more. Shared only with the release’s name for the Lean statement or OpenAI’s note on it: nonzero, nearest, neighbor, uniform, direction and positive.
  • Proposition 3.7 of Directional transience implies ballisticity. Words of the Lean statement, its names split into words, that also appear in the theorem: measured, pi, site, environment, path, probability and two more.
  • Theorem 1.1 of A directional zero–one law for finite-range-dependent random environments. Words of the Lean statement, its names split into words, that also appear in the theorem: one, zero, directional and law. Found in the paper’s title, which its main theorem states: environments.
  • Proposition 7.1 of A directional zero–one law under strict ellipticity. Words of the Lean statement, its names split into words, that also appear in the theorem: site, count, directional, probability and eq. Shared only with the release’s name for the Lean statement or OpenAI’s note on it: positive.

How Atlas selects possible matches: it compares words in the Lean statement with every statement in the family. It also splits Lean names into words. The release’s label and note receive less weight; a main theorem wins a close match. If the Lean wording yields no clear match, Atlas uses the catalogue description. This selects passages to compare; it does not establish that they mean the same thing.

Reported Comparator runs

two independent groups report that Comparator accepted runs for this Lean statement file: Carlos Toledo’s cert-machine; MathVet. Each group reports its own Comparator run for this statement file. Atlas has not repeated the runs.

For a configured theorem, Comparator tests whether OpenAI’s proof proves the exact Lean statement. Some files instead configure definitions for comparison by name and type. Acceptance does not establish that the statement means the same thing as the paper’s theorem.

Carlos Toledo’s cert-machine

How they ran it, in their words

Every Comparator challenge re-run on Linux with nanoda switched on, decided by a preregistered rule; every family’s challenge statements read against OpenAI’s headline, clause by clause. Decider: Comparator (leanprover/comparator d03acab1 = tag v4.34.0, built with the release’s toolchain v4.34.1), lean4export 076e8e57, landrun 811cfff5, nanoda_lib 3a240721 — on GitHub’s Linux runners (.github/workflows/openai-math-kernel.yml), one j…

  • Accepted Their term: “CERTIFIED”.

    Re-run through Comparator with the independent nanoda kernel switched on: Lean’s kernel and nanoda both accept OpenAI’s solution.

    Reported 10 October 2026, at the release version shown here. Original verification report

MathVet

How they ran it, in their words

An independent, model-assisted, pre-referee reading of each family’s challenge statements against its headline claim under a published rubric (PROTOCOL.md), with its own Comparator runs per challenge. Its protocol describes a planned error-rate study; this import does not establish that the study has been completed.

  • Accepted Their term: “comparator-sandboxed-pass”.

    Re-run through Comparator in a sandboxed virtual machine: accepted.

    Reported 8 October 2026, at the release version shown here. Original verification report

What an accepted Comparator run would establish

If Comparator is run under this configuration and accepts, the solution proves the configured theorem using only the allowed axioms, and the Lean kernel accepts every step.

This configuration lists no definition holes, so every definition the statement uses is compared as it is written in this file.

Allowed axioms: propext, Quot.sound, Classical.choice

Acceptance leaves open whether the Lean statement means the same thing as the paper’s theorem, whether the paper’s other claims are correct, and whether the result is new. Those questions require comparing the definitions and statements, reviewing the paper’s arguments, and reading the earlier literature.

Do family 220’s Lean statements express the advertised result?

These assessments compare all the family’s Lean statements with the whole result OpenAI describes in its catalogue. They do not assess this statement alone. Each group uses its own published rules.

Neither group finds that the Lean statements express or imply the whole advertised result. They describe what the statements express in different terms.

  • MathVet

    Finds part of it stated, or a narrower or weaker statement Their term: “partial”.

    Only a special case is stated, or a co-equal headline claim has no challenge statement. Their record

    Their note: Stated: directional_zero_one (d) (hd : 3 ≤ d) (hell : StrictEllipticity μ) (ℓ ≠ 0) : annealed μ 0 (escape ℓ) = 0 ∨ ... = 1 for IID environments (environmentLaw μ = infinitePi (fun _ => μ)), and directional_transience_implies_ballisticity (d >= 2, iid uniformly elliptic, DirectionallyTransient ν ℓ → ∃ v, 0 < dot v ℓ ∧ HasVelocity ν v), plus the velocity-hemisphere refinement. Not stated: the zero-one law for stationary ergodic finite-range-dependent environments under uniform ellipticity (the docs title says 'beyond iid environments' but the scope and Lean are iid only).

  • Carlos Toledo’s cert-machine

    Finds part of it stated, or a narrower or weaker statement Their term: “NARROWER — UNLINKED”.

    The challenge statements state less than the headline; the missing part comes from a paper the Lean note does not link. Their record

    Their note: The directional zero–one law for stationary ergodic finite-range-dependent uniformly elliptic environments is claimed but not stated by any family-220 challenge.

Read the complete assessments on the family page.

OpenAI’s own note on what this Lean statement covers

“The formalization proves this for nearest-neighbor walks in independent identically distributed strictly elliptic environments on $\mathbb Z^d$, for every $d\ge3$ and every nonzero real direction. Strict ellipticity means that every allowed transition probability is positive almost surely; no uniform positive lower bound or moment condition is assumed. The probability is the annealed law from the origin.”

An AI agent drafted an interpretation of that note, classifying this statement as “states a paper’s theorem as the paper does”. No human review of the draft is recorded.

Supporting material

The complete Lean statement file

92 lines, copied from release version fd4aeeb. A name defined in this file links to its line; pointing at the name shows its definition.

Declared in this fileOpenAI’s library at fd4aeebOther linked names open the current documentation for Mathlib, Lean’s mathematical library.

Links in the file: 42 to its own declarations, 61 to Mathlib’s documentation. 15 declared names also link to the same declaration in OpenAI’s library. 1 identifier stays plain because it resolves to no single declaration: a variable Lean binds automatically, notation, or a name the scan of the pinned sources did not find. OpenAI uses Mathlib version d13f23b. The linked documentation describes the current version, so names that have since changed may be missing there.

import Mathlibnamespace OAIopen MeasureTheory ProbabilityTheory Filter Preorderopen scoped ENNReal BigOperators Topologynamespace DirectionalZeroOneabbrev Site (d : ℕ) := Fin d → ℤabbrev Step (d : ℕ) := Fin d × Booldef stepVector {d : ℕ} (e : Step d) : Site d :=  fun i => if i = e.1 then (if e.2 then 1 else -1) else 0def Row (d : ℕ) :=  {p : Step d → ℝ // (∀ e, p e ∈ Set.Icc (0 : ℝ) 1) ∧ ∑ e, p e = 1}instance (d : ℕ) : MeasurableSpace (Row d) := inferInstanceAs  (MeasurableSpace {p : Step d → ℝ //    (∀ e, p e ∈ Set.Icc (0 : ℝ) 1) ∧ ∑ e, p e = 1})abbrev Environment (d : ℕ) := Site d → Row dabbrev Path (d : ℕ) := ℕ → Site dabbrev State (d : ℕ) := Environment d × Site ddef StrictEllipticity {d : ℕ} (μ : Measure (Row d)) : Prop :=  ∀ᵐ p ∂μ, ∀ e, 0 < p.val enoncomputable def environmentLaw {d : ℕ} (μ : Measure (Row d))    [IsProbabilityMeasure μ] : Measure (Environment d) :=  Measure.infinitePi (fun _ => μ)noncomputable def transition (d : ℕ) : Kernel (State d) (State d) where  toFun s := ∑ e : Step d,    ENNReal.ofReal ((s.1 s.2).val e) • Measure.dirac (s.1, s.2 + stepVector e)  measurable' := by    apply measurable_from_prod_countable_left    intro x    apply Finset.measurable_sum    intro e he    apply Measure.measurable_of_measurable_coe    intro t ht    simp only [Measure.smul_apply, smul_eq_mul]    apply Measurable.mul    · exact (measurable_pi_apply e |>.comp        (measurable_subtype_coe.comp (measurable_pi_apply x))).ennreal_ofReal    · exact (Measure.measurable_coe ht).comp        (Measure.measurable_dirac.comp (measurable_id.prodMk measurable_const))instance (d : ℕ) : IsMarkovKernel (transition d) where  isProbabilityMeasure s := by    constructor    change (∑ e : Step d,      ENNReal.ofReal ((s.1 s.2).val e) •        Measure.dirac (s.1, s.2 + stepVector e)) Set.univ = 1    simp only [Measure.finsetSum_apply, Measure.smul_apply,      Measure.dirac_apply_of_mem (Set.mem_univ _), smul_eq_mul, mul_one]    rw [← ENNReal.ofReal_sum_of_nonneg]    · rw [(s.1 s.2).property.2, ENNReal.ofReal_one]    · intro e he      exact ((s.1 s.2).property.1 e).1noncomputable def historyKernel (d n : ℕ) :    Kernel ((i : Finset.Iic n) → State d) (State d) :=  (transition d).comap (fun h => h ⟨n, Finset.mem_Iic.mpr le_rfl⟩)    (measurable_pi_apply _)instance (d n : ℕ) : IsMarkovKernel (historyKernel d n) := by  unfold historyKernel  infer_instancenoncomputable def initialLaw {d : ℕ} (μ : Measure (Row d))    [IsProbabilityMeasure μ] (x : Site d) : Measure (State d) :=  (environmentLaw μ).map (fun ω => (ω, x))noncomputable def annealed {d : ℕ} (μ : Measure (Row d))    [IsProbabilityMeasure μ] (x : Site d) : Measure (Path d) :=  (Kernel.trajMeasure (X := fun _ => State d) (initialLaw μ x) (historyKernel d)).map    (fun z n => (z n).2)def escape {d : ℕ} (ℓ : Fin d → ℝ) : Set (Path d) :=  {X | Tendsto (fun n => ∑ i, (X n i : ℝ) * ℓ i) atTop atTop}theorem directional_zero_one (d : ℕ) (hd : 3 ≤ d)    (μ : Measure (Row d)) [IsProbabilityMeasure μ]    (hell : StrictEllipticity μ) (ℓ : Fin d → ℝ) (hℓ : ℓ ≠ 0) :    annealed μ 0 (escape ℓ) = 0 ∨ annealed μ 0 (escape ℓ) = 1 := by sorryend DirectionalZeroOneend OAI
Every extracted statement of the accompanying papers

The statements the atlas extracted automatically from each accompanying paper’s TeX source, with links to the full sources.

A directional zero–one law under strict ellipticity

Theorem

Let d\ge3, let \PP be an independent and identically distributed law of nearest-neighbor transition rows on \ZZ^d satisfying (eq:ellipticity), and let \ell\in\RR^d\setminus\{0\}. Then

P_0(A_\ell)\in\{0,1\}.
Section 1, Introduction Read it in the paper TeX source, line 61
Show the TeX
Let $d\ge3$, let $\PP$ be an independent and identically distributed
law of nearest-neighbor transition rows on $\ZZ^d$ satisfying
\eqref{eq:ellipticity}, and let $\ell\in\RR^d\setminus\{0\}$.
Then
\[
 P_0(A_\ell)\in\{0,1\}.
\]

Directional transience implies ballisticity

Theorem (Directional transience implies ballisticity)

Let d\ge2 and let P=\nu^{\otimes\mathbb Z^d} be an iid law of nearest-neighbor transition rows satisfying uniform ellipticity. If \ell\in S^{d-1} and P_0(A_\ell)=1, then there exists a deterministic vector v=v(\nu)\in\mathbb R^d such that

v\cdot\ell>0, \qquad P_0\!\left(\lim_{n\to\infty}\frac{X_n}{n}=v\right)=1.

In particular, the walk is ballistic in the same direction \ell.

Section 1, Introduction Read it in the paper TeX source, line 50
Show the TeX
Let $d\ge2$ and let $P=\nu^{\otimes\mathbb Z^d}$ be an iid law of
nearest-neighbor transition rows satisfying uniform ellipticity. If
$\ell\in S^{d-1}$ and $P_0(A_\ell)=1$, then there exists a deterministic
vector $v=v(\nu)\in\mathbb R^d$ such that
\[
 v\cdot\ell>0,
 \qquad
 P_0\!\left(\lim_{n\to\infty}\frac{X_n}{n}=v\right)=1.
\]
In particular, the walk is ballistic in the same direction $\ell$.
Corollary (Positive-probability transience and the velocity hemisphere)

Let d\ge3 and let P=\nu^{\otimes\mathbb Z^d} be an iid law of nearest-neighbor transition rows satisfying uniform ellipticity. For a fixed \ell\in\mathbb R^d\setminus\{0\}, set A_\ell=\{X_n\cdot\ell\longrightarrow+\infty\}. If P_0(A_\ell)>0, then there is a deterministic nonzero vector v=v(\nu) such that

v\cdot\ell>0, \qquad P_0\!\left(\lim_{n\to\infty}\frac{X_n}{n}=v\right)=1.

If such a direction exists, then the deterministic sets of directions satisfy

\{u\in S^{d-1}:P_0(A_u)=1\} =\{u\in S^{d-1}:P_0(A_u)>0\} =\{u\in S^{d-1}:v\cdot u>0\}.

In particular, P_0(A_u)=0 for each fixed u\in S^{d-1} with v\cdot u\le0, including every equator direction. The equality concerns annealed probabilities for each fixed deterministic direction, not a simultaneous pathwise assertion over all directions.

Section 1, Introduction Read it in the paper TeX source, line 205
Show the TeX
Let $d\ge3$ and let $P=\nu^{\otimes\mathbb Z^d}$ be an iid law of
nearest-neighbor transition rows satisfying uniform ellipticity. For a
fixed $\ell\in\mathbb R^d\setminus\{0\}$, set
$A_\ell=\{X_n\cdot\ell\longrightarrow+\infty\}$. If $P_0(A_\ell)>0$,
then there is a deterministic nonzero vector $v=v(\nu)$ such that
\[
 v\cdot\ell>0,
 \qquad
 P_0\!\left(\lim_{n\to\infty}\frac{X_n}{n}=v\right)=1.
\]
If such a direction exists, then the deterministic sets of directions
satisfy
\[
 \{u\in S^{d-1}:P_0(A_u)=1\}
 =\{u\in S^{d-1}:P_0(A_u)>0\}
 =\{u\in S^{d-1}:v\cdot u>0\}.
\]
In particular, $P_0(A_u)=0$ for each fixed $u\in S^{d-1}$ with
$v\cdot u\le0$, including every equator direction. The equality concerns
annealed probabilities for each fixed deterministic direction, not a
simultaneous pathwise assertion over all directions.
Configuration and file facts
OpenAI’s Lean catalogue
OpenAI’s Lean catalogue does not list this as a main result; the release’s Lean notes for family 220 link it.
Solution module
OAI.Probability.DirectionalWalk.Main
Allowed axioms
propext, Quot.sound, Classical.choiceThe axioms this configuration allows a proof to use. A replay shows which of them a proof uses.
Imports
Mathlib
Imports from outside Mathlib
None
Local vocabulary
17 local vocabulary declarations
Lines of Lean, without comments or blank lines
65
Second proof-verification program (nanoda)
Off in OpenAI's configuration.

Statement comparison

A shareable summary of this page: the proposed paper match, what the Lean statement expresses, and which reviews are recorded.

Plectis Atlas

Directional zero–one law under strict ellipticity

Family 220: Directional zero–one laws beyond iid environments and iid ballisticity

Candidate pairing

Theorem

Let d\ge3, let \PP be an independent and identically distributed law of nearest-neighbor transition rows on \ZZ^d satisfying (eq:ellipticity), and let \ell\in\RR^d\setminus\{0\}. Then

P_0(A_\ell)\in\{0,1\}.

A directional zero–one law under strict ellipticity

TeX label thm:main, build/01-introduction.tex, line 61

The Lean statement says

theorem directional_zero_one (d : ℕ) (hd : 3 ≤ d)    (μ : Measure (Row d)) [IsProbabilityMeasure μ]    (hell : StrictEllipticity μ) (ℓ : Fin d → ℝ) (hℓ : ℓ ≠ 0) :    annealed μ 0 (escape ℓ) = 0 ∨ annealed μ 0 (escape ℓ) = 1 := by sorry

A Lean statement states the theorem and leaves its proof as sorry on purpose. OpenAI’s proof is in a separate solution module, and a program called Comparator checks that proof against this statement.

Atlas selected this possible match because the two statements share words. No review of whether they mean the same thing is recorded.two independent groups report that Comparator accepted runs for this file at the release version shown here.Statement review: none recorded

17 local vocabulary declarationsAllowed axioms: propext, Quot.sound, Classical.choiceopenai/math at fd4aeebwcook04.github.io/plectis-atlas/statements/DirectionalWalk.html

Recorded comparisons with the paper

Atlas records no contributed comparison of this statement with the paper.

Contributed Comparator run reports

Atlas records no contributed report of running Comparator for this statement file.

Questions to resolve when comparing this statement with the paper

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