Codex reports equal-capacity greedy-matching dominance

In Arnosti’s random bipartite matching model with independent uniform job neighbourhoods of prescribed sizes and a common positive integer bin capacity, RANDOM-VERTEX stochastically dominates RANKING in the number of accepted jobs.

Sources for this record

What was already known

Arnosti proved equality in distribution at capacity one and dominance at capacity two, and conjectured the comparison for larger common capacities.

AI involvement AI-led

The project credits OpenAI Codex with the central proof, Lean formalization and verification tooling; a human directed the project, requested simplification and reviewed presentation.

The project credits Codex with the central stochastic-dominance proof, Lean formalization and verification tools. A human directed the project, requested simplification and reviewed presentation. The division of mathematical work supports AI-led involvement.

Importance Notable

Settles the equal-capacity comparison for all finite instances of Arnosti’s random-neighbourhood model.

Limitations

The comparison is over random graphs and algorithm choices; it is not run-by-run dominance, a fixed-graph theorem or a result for unequal capacities. External expert review remains open.

Technical verification Formal (Lean 4)

The pinned repository reports a public Lean build of 91 positive modules, including the final source-model theorem, and prints only standard axioms. This is a source-reported machine check of the scoped stochastic-dominance statement; AIProofWatch did not rerun it.

Formal checking

The repository reports a public Lean build of 91 positive modules from commit c521b8d45bfa8a38b60a8e55b5ab104634d48b49, including the final source-model theorem, with only standard axioms printed.

Checker
Lean kernel, as reported by MathIsEvenEasier
Scope
In Arnosti’s random bipartite matching model with independent uniform job neighbourhoods of prescribed sizes and a common positive integer bin capacity, RANDOM-VERTEX stochastically dominates RANKING in the number of accepted jobs.
Basis
Reported by the linked checker
Evidence source

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

Human understanding Few

Few is the default when evidence for a higher level is insufficient. The sources describe human direction and presentation review but do not document a named person explaining the central proof. Few is the default from this evidence gap, not a finding that people cannot understand it.

Correction and publication history

2026-10-18 · publication

Primary theorem, prior baseline, AI attribution and documented proof scope reviewed for non-notifying local inclusion.

Read this published revision