Benchmark Almanac

Riemann-bench

Gemini 4 Carbon 80% leads since Oct 2026 In use

25 private research-mathematics problems from professors and IMO medalists. Agents with tools, 100 runs per problem.

In the authors’ words

Recent AI systems have achieved gold-medal-level performance on the International Mathematical Olympiad, demonstrating remarkable proficiency at competition-style problem solving. However, competition mathematics represents only a narrow slice of mathematical reasoning: problems are drawn from limited domains, require minimal advanced machinery, and can often reward insightful tricks over deep theoretical knowledge. We introduce Riemann-Bench, a private benchmark of expert-curated problems designed to evaluate AI systems on research-level mathematics that goes far beyond the olympiad frontier. Problems are authored by Ivy League mathematics professors, graduate students, and PhD-holding IMO medalists, and routinely took their authors weeks to solve independently. Each problem undergoes double-blind verification by two independent domain experts who must solve the problem from scratch, and yields a unique, closed-form solution assessed by programmatic verifiers. We evaluate frontier models as unconstrained research agents, with full access to coding tools, search, and open-ended reasoning, using an unbiased statistical estimator computed over 100 independent runs per problem. Our results reveal that all frontier models currently score below 10%, exposing a substantial gap between olympiad-level problem solving and genuine research-level mathematical reasoning. By keeping the benchmark fully private, we ensure that measured performance reflects authentic mathematical capability rather than memorization of training data.

Abstract of Riemann-Bench: A Benchmark for Moonshot Mathematics (arXiv:2604.06802, CC0)
Made by Surge AI Released Apr 2026 Research mathematics Tasks kept private Last in a launch post Oct 2026 Last model added Oct 2026
Level
Research frontier Researchers, on open problems or tasks that take days
Scored
Checked automatically A program checks the result against an answer key, unit tests or the expected final state.
Answers
Short answer A number, word or short string matched to a key.
4
Models scored in lab cards
3
Launch posts list it, from 2 labs
2
System cards report it, from 2 labs

Gemini 4 Carbon leads with 80%

Best score per model as labs report them in their own cards. Labs pick their own settings, so these compare less cleanly than independent runs.

  1. 1 Gemini 4 Carbon 80%
  2. 2 Gemini 4 Argon 76%
  3. 3 Claude Opus 5 60%
  4. 4 Claude Fable 5 55%
#ModelScoreSettingDateSource
1 Gemini 4 Carbon 80% Oct 2026 Model card
2 Gemini 4 Argon 76% Oct 2026 Model card
3 Claude Opus 5 60% Jul 2026 Model card
4 Claude Fable 5 55% Jun 2026 Model card

4 models have held number one since its release in Apr 2026

Lab claims count from the day the card came out, independent runs from the model’s release.

Anthropic Google DeepMind
Lab claims 4 leaders

Scores over time

All the scores we have, one dot each, so a model tested at several settings appears more than once.

Reported by the lab in its model card Best so far
0% 20% 40% 60% 80% 100% 2026 2027 Near the ceiling (85%) Gemini 4 Carbon Claude Opus 5 Claude Fable 5 0% 20% 40% 60% 80% 100% 2026 2027 Near the ceiling (85%) Gemini 4 Carbon Claude Opus 5

2 labs put it in a launch post in the last six months

Launch posts from every lab that has listed it, one tick per post. Tall colored ticks include it, and short gray ones leave it out.

Anthropic
Google DeepMind
DateLaunch postScoreAs the post writes it
28 Oct 2026 Gemini 4 Carbon 80 RiemannBench
13 Oct 2026 Gemini 4 Argon 76 RiemannBench
9 Jun 2026 Claude Fable 5 55 RiemannBench

2 system cards report it, from 2 labs

Besides launch posts, we read the system cards, model cards and technical reports labs publish with a release. They report far more, including safety and frontier-risk tests.

DateDocumentScoreAs the document writes itSection
13 Oct 2026 Gemini 4 Argon model card 76 RiemannBench (results table, p.5) Capabilities
24 Jul 2026 Claude Opus 5 system card 60 RiemannBench, max effort without tools, mean of 4 attempts (79% with tools), printed on chart (8.7, Figure 8.7.A) Capabilities

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