Deimos R1

Kozu AI Research ยท 4.54B ยท Apache 2.0
BF16 weights Reasoning + instruction Report DR1-2026.07
Small model. Disciplined reasoning.

Release brief

01

Deimos R1 is a focused 4B-class system for reasoning and instruction following. In like-for-like evaluation, it improves five of seven reported full-budget capability rows while using substantially fewer thinking tokens on the headline tasks.

The central result is efficiency, not scale. Deimos R1 reaches 0.907 GSM8K flexible and 0.551 MMLU-Pro in the recorded full-budget run while reducing mean thinking tokens by 5.0ร— and 2.9ร— respectively.

5.0ร—fewer GSM8K think tokens
+0.188MMLU-Pro absolute delta
0.465held-out reasoning accuracy ยท n=200

Evaluation

02

The table reports matched comparisons under the same open harness, generation budget, sampling settings, and seed. Values are run-local and should not be compared with vendor-published numbers produced by other evaluation stacks.

Full-budget benchmarkReferenceDeimos R1DeltaThink tokens ยท ref โ†’ R1
GSM8K ยท flexible0.8600.907+0.0471,778 โ†’ 357
MMLU-Pro0.3630.551+0.1881,984 โ†’ 677
IFEval ยท prompt loose0.2600.353+0.0934,808 โ†’ 1,189
IFEval ยท instruction loose0.4370.487+0.050โ€”
IFEval ยท prompt strict0.2600.267+0.007โ€”
IFEval ยท instruction strict0.4370.429โˆ’0.008โ€”
GSM8K ยท strict format0.7270.333โˆ’0.394โ€”

lm-eval 0.4.12 ยท 32,768-token generation budget ยท temperature 1.0 ยท top_p 0.95 ยท presence penalty 1.5 ยท thinking enabled ยท GSM8K/IFEval n=150 ยท MMLU-Pro n=25 per subtask ยท seed 42.

4,096-token constrained runReferenceDeimos R1Delta
GSM8K ยท flexible0.6600.933+0.273
MMLU-Pro0.3940.634+0.240
IFEval ยท prompt strict0.2470.320+0.073

Constrained-budget results use greedy decoding. Compare within this table, not across decoding regimes.

  • The internal held-out math set is contamination-filtered with verified ground truth: accuracy moved from 0.175 to 0.465 at n=200. The 12-check instruction suite remained 0.917.
  • IFEval scores the complete response, including the thinking block. Shorter reasoning can therefore improve constraint scores; the behavior affects both compared models.
  • GSM8K strict rewards an unrequested #### N ending. Deimos R1 is materially weaker at silently copying that demonstrated format. Explicit format requests are more reliable.
  • Raw evaluation artifacts are retained under bench/ in this repository.

Data & development

03

kozu_reasoning_v1.1 is a roughly 10k-example blend of verified reasoning traces and human-authored instruction data. The release uses a three-layer quality process for the reasoning portion and a dedicated 800-example format-adherence slice.

Reasoning ยท ~5kKozuโ€™s Kuiper trace inverter was designed to recreate Mythos/Fable-style reasoning from answer-scrubbed human reference solutions in GSM8K and NuminaMath 1.5. Retained traces passed symbolic answer verification, derivation checks, deterministic defect scans, and an adversarial judge panel.
Instruction ยท ~5kHuman-authored pairs used from Databricks Dolly 15k and OpenAssistant OASST2.
Format ยท 800Deterministic rewraps of verified rows for explicitly requested formats including JSON, boxed answers, and named answer markers.
Source licenses and attribution
GSM8K: MIT. NuminaMath 1.5: Apache-2.0. Databricks Dolly 15k: CC-BY-SA-3.0. OpenAssistant OASST2: Apache-2.0. Reasoning traces were generated with Kuiper-R1 by Kozu AI.

Deployment

04

The repository includes merged BF16 weights, tokenizer assets, processor configuration, generation configuration, and the model chat template. Thinking is enabled by default and appears inside <think>โ€ฆ</think> before the final answer.

vllm serve Michael-Kozu/Deimos-R1 --served-model-name deimos-r1 \
  --max-model-len 8192 --gpu-memory-utilization 0.80 --trust-remote-code

Recommended sampling: temperature 0.6โ€“1.0 and top_p 0.95. Request required output formats explicitly.

Limitations

05
  • This is a research preview, not a safety-certified or production-guaranteed system.
  • The strongest evidence covers English reasoning and instruction following. Performance outside those domains is not established here.
  • Silent few-shot format imitation is a known weakness; strict GSM8K formatting declines substantially in the recorded comparison.
  • Long reasoning may still be incorrect. Verify outputs for consequential decisions and domain-specific use.
Kozu AI ยท Deimos R1Apache-2.0 ยท Model release
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