StochBench brings graduate stochastic processes into Lean theorem-proving evaluation

The benchmark covers Markov chains, renewal processes, random walks, martingales, stopping times, queues, Brownian motion, stochastic calculus, weak convergence, Poisson processes and continuous-time Markov processes.

What happened?

The StochBench paper introduced 450 Lean 4 problems in graduate stochastic processes paired with natural-language sources; the authors report that an Opus 4.8-based proof agent solved 157 of 450 targets within a 15-minute per-problem budget, a 34.9% proof rate.

The benchmark covers Markov chains, renewal processes, random walks, martingales, stopping times, queues, Brownian motion, stochastic calculus, weak convergence, Poisson processes and continuous-time Markov processes. Its released dataset distinguishes 114 direct formalizations from 336 abstracted targets that expose assumptions explicitly when the required stochastic-process infrastructure is not available in the fixed Lean/Mathlib environment.

Why it matters

Formal theorem-proving benchmarks can overstate general mathematical coverage when they concentrate on domains already well represented in proof libraries. StochBench makes domain breadth and library-support limitations part of the evaluation surface, providing a harder test of whether proof agents can operate in applied mathematics with substantial formalization gaps.

Significance rationale: StochBench is a field-level benchmark milestone because it moves Lean theorem-proving evaluation beyond predominantly competition and textbook-style mathematics into a broad graduate applied-mathematics domain, while explicitly representing the gap between direct formalization and abstraction needed when library support is incomplete.

Historical context

Primary evidence

Evidence & status at a glance

Significance
H2 · Field milestone
Verification
Paper released
Evidence level
E3 · Inspectable artifact
AI role
Substantive AI support
Formal assurance
Artifact available

How should these labels be read? →

Contribution & verification

Mathematical novelty
Tooling only
Interface
Informal, Formal, Hybrid
AI contribution
An Opus 4.8-based formalizer assisted in expressing human-written benchmark problems as Lean statements, with Lean feedback and human revision, and an Opus 4.8-based proof agent supplied the reported baseline proofs.
Human contribution
Researchers selected and wrote the benchmark-specific problems, definitions, hypotheses and evaluation protocol, reviewed the formal statements against their source problems, fixed the Lean/Mathlib environment and analyzed the baseline results by topic and representation.
Verification
Paper released · E3 · Inspectable artifact · Artifact available
Last reviewed
2026-09-14

Technical details

Systems
stochbench, lean
Organizations
case-western-reserve-university
Problems
stochastic-processes, graduate-applied-mathematics
Methods
benchmarking, lean-formalization, proof-agents, autoformalization

Sources & artifacts

Verification history

  • 2026-09-08 · Paper released · E2 · Research record

    The arXiv research record defines the 450-problem benchmark, its stochastic-process scope and the reported 157/450 baseline under a 15-minute per-problem budget.

  • 2026-09-14 · Paper released · E3 · Inspectable artifact

    The public StochBench dataset exposes the informal statements, Lean statements, representation labels and stored proof records. E3 records artifact-level inspectability and does not imply an independent replay of the full baseline evaluation.

Corrections

No corrections recorded.