Benchmark Almanac

Riemann-bench

GPT-5.6 Sol 83.2% leads since July 2026
GPT-5.6 Sol 83.2% leads since July 2026
In use

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

Made by
Surge AI
Released
April 2026
Kind
Research mathematics
Level
Research frontier
Scored
Checked automatically
Answers
Short answer
Tasks
Kept private
Strongest model tested
Gemini 4 Carbon #2 on the capability index
Last in a launch post
October 2026
Last model added
October 2026
Scores refreshed
November 12th, 2026

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)
21
Entries on its own leaderboard, 20 models we track
3
Launch posts list it, from 2 labs
2
System cards report it, from 2 labs

GPT-5.6 Sol leads with 83.2%

Best score per entry from the benchmark's own leaderboard, read on November 12th, 2026. Where a model ran with several settings or harnesses, we keep its best. Names in gray aren't in our model list: fine-tunes, agent systems, products and older models. They don't count toward leaders.

GPT-5.6 Sol leads with 83.2%, claims included

Best score per model from every source, including labs’ own numbers and claims Epoch AI collected from reports and papers. Labs pick their own settings, so a claim can beat an independent run of the same model.

  1. 1 GPT-5.6 Sol max 83.2%
  2. 2 GPT-6 Astra max 81.6%
  3. 3 Claude Opus 5.5 adaptive/max 80%
  4. 4 Gemini 4 Carbon high 80%
  5. 5 GPT-6.1 Sol max 79.2%
  6. 6 Claude Sonnet 5.5 adaptive/max 76.8%
  7. 7 Gemini 4 Argon high 74.4%
  8. 8 Claude Fable 5.1 adaptive/max 71.2%
  9. 9 Muse Wonder Full max 63.2%
  10. 10 Kimi K3.1 Pro max 60.8%
  11. 11 Muse Wonder 1.0 max 59.2%
  12. 12 Grok 4.7 xhigh 57.6%
  13. 13 Gemini 3.8 Flash high 56.8%
  14. 14 Muse Spark 1.3 xhigh 53.6%
  15. 15 Qwen 3.8 Max xhigh 48%
  16. 16 DeepSeek V4.1 Flash 1017 max 38.4%
  17. 17 Beam 1.0 max 37.6%
  18. 18 Kimi K3 max 36.8%
  19. 19 Tencent Hy4 preview high 24%
  20. 20 GLM-5.3 max 20.8%
  21. 21 Mistral Large 4 high 20%

Source: Official Riemann-bench leaderboard

#EntryScoreSettingDateSource
1 GPT-5.6 Sol 83.2% max Jul 2026 Official leaderboard
2 GPT-6 Astra 81.6% max Sep 2026 Official leaderboard
3 Claude Opus 5.5 80% adaptive/max Sep 2026 Official leaderboard
4 Gemini 4 Carbon 80% high Oct 2026 Official leaderboard
5 GPT-6.1 Sol 79.2% max Sep 2026 Official leaderboard
6 Claude Sonnet 5.5 76.8% adaptive/max Sep 2026 Official leaderboard
7 Gemini 4 Argon 74.4% high Sep 2026 Official leaderboard
8 Claude Fable 5.1 71.2% adaptive/max Sep 2026 Official leaderboard
9 Muse Wonder Full 63.2% max Oct 2026 Official leaderboard
10 Kimi K3.1 Pro 60.8% max Oct 2026 Official leaderboard
11 Muse Wonder 1.0 59.2% max Official leaderboard
12 Grok 4.7 57.6% xhigh Sep 2026 Official leaderboard
13 Gemini 3.8 Flash 56.8% high Sep 2026 Official leaderboard
14 Muse Spark 1.3 53.6% xhigh Sep 2026 Official leaderboard
15 Qwen 3.8 Max 48% xhigh Aug 2026 Official leaderboard
16 DeepSeek V4.1 Flash 1017 38.4% max Oct 2026 Official leaderboard
17 Beam 1.0 37.6% max Oct 2026 Official leaderboard
18 Kimi K3 36.8% max Jul 2026 Official leaderboard
19 Tencent Hy4 preview 24% high Aug 2026 Official leaderboard
20 GLM-5.3 20.8% max Aug 2026 Official leaderboard
21 Mistral Large 4 20% high Oct 2026 Official leaderboard
#ModelScoreSettingDateSource
1 GPT-5.6 Sol 83.2% max Jul 2026 Official leaderboard
2 GPT-6 Astra 81.6% max Sep 2026 Official leaderboard
3 Claude Opus 5.5 80% adaptive/max Sep 2026 Official leaderboard
4 Gemini 4 Carbon 80% high Oct 2026 Official leaderboard
5 GPT-6.1 Sol 79.2% max Sep 2026 Official leaderboard
6 Claude Sonnet 5.5 76.8% adaptive/max Sep 2026 Official leaderboard
7 Gemini 4 Argon 76% Oct 2026 Lab model card
8 Claude Fable 5.1 71.2% adaptive/max Sep 2026 Official leaderboard
9 Muse Wonder Full 63.2% max Oct 2026 Official leaderboard
10 Kimi K3.1 Pro 60.8% max Oct 2026 Official leaderboard
11 Claude Opus 5 60% Jul 2026 Lab model card
12 Grok 4.7 57.6% xhigh Sep 2026 Official leaderboard
13 Gemini 3.8 Flash 56.8% high Sep 2026 Official leaderboard
14 Claude Fable 5 55% Jun 2026 Lab model card
15 Muse Spark 1.3 53.6% xhigh Sep 2026 Official leaderboard
16 Qwen 3.8 Max 48% xhigh Aug 2026 Official leaderboard
17 DeepSeek V4.1 Flash 1017 38.4% max Oct 2026 Official leaderboard
18 Beam 1.0 37.6% max Oct 2026 Official leaderboard
19 Kimi K3 36.8% max Jul 2026 Official leaderboard
20 Tencent Hy4 preview 24% high Aug 2026 Official leaderboard
21 GLM-5.3 20.8% max Aug 2026 Official leaderboard
22 Mistral Large 4 20% high Oct 2026 Official leaderboard

Labs report scores for 4 models in their cards. Switch the scores above to rank them together.

Number one over time 2 models have held number one with claims included since its release in April 2026

Lab claims count from the day the card came out, independent runs from the model’s release. We draw one row each for the benchmark’s own leaderboard and what labs claim in their cards.

OpenAI Anthropic Google DeepMind
Own leaderboard 1 leader
GPT-5.6 Sol 83.2%
Lab claims 4 leaders

Sources: Official Riemann-bench leaderboard and labs’ model cards

Scores over time

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

On the benchmark’s own leaderboard Reported by the lab in its model card Best so far
0% 20% 40% 60% 80% 100% 2026 2027 Near the ceiling (85%) GPT-5.6 Sol Claude Fable 5 0% 20% 40% 60% 80% 100% 2026 2027 Near the ceiling (85%) GPT-5.6 Sol Claude Fable 5

Sources: Official Riemann-bench leaderboard and labs’ model cards

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
Oct 28, 2026 Gemini 4 Carbon 80 RiemannBench
Oct 13, 2026 Gemini 4 Argon 76 RiemannBench
Jun 9, 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
Oct 13, 2026 Gemini 4 Argon model card 76 RiemannBench (results table, p.5) Capabilities
Jul 24, 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

2 lab claims next to the leaderboard

Each score a lab reported for its own model, beside the same model's best score on the leaderboard. Gaps mostly come from different harnesses, effort levels and task subsets. 1 of them match, which usually means one side copied the other. Every benchmark.

Model Lab says Board says Gap
Gemini 4 Argon 76% RiemannBench 74.4% Leaderboard, high +1.6 pts
Gemini 4 Carbon 80% RiemannBench 80% Leaderboard, high Same

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