Atomight-V2.5-1.7B-C1

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Atomight V2.5 1.7B, our most capable and intelligent model yet, is a multi-domain reasoning model built on Qwen3-1.7B, trained with GRPO (Group Relative Policy Optimization) across STEM, science, math, and code, using a curated six-dataset stack in a streaming round-robin setup — trained entirely on a single Colab free-tier T4 GPU. Note: This is only the first checkpoint model of Atomight-V2.5-1.7B, but still usable and powerful model.

Overview

Atomight-V2.5 is post-trained from Qwen/Qwen3-1.7B (already instruct/chat-capable) using memory-efficient chunked GRPO to fit T4 VRAM constraints. Training data spans four domains, each selected for having genuinely verifiable rewards (exact-match answers or executable test cases) rather than relying purely on LLM-judged quality:

Domain Dataset(s) Role
STEM Logics-MLLM/Logics-STEM-SFT-Dataset-Open-5.3M Broad STEM coverage, difficulty-annotated
Science MegaScience/MegaScience Science-specific depth, ablation-selected subsets
Math nvidia/OpenMathReasoning, zwhe99/DeepMath-103K Verifiable-answer CoT and RL-native reward data
Code nvidia/OpenCodeInstruct Instruction-tuned code generation with test cases

Reward shaping combines an XML-format reward (<thinking> / <answer> tag structure) with an exact-match correctness reward, evaluated via trl's GRPOTrainer on 4-bit QLoRA (Unsloth).

Benchmark Results

Evaluated with EleutherAI's lm-evaluation-harness, standard few-shot settings, no sample limiting.

Benchmark Score
GSM8K (strict-match) 69.6%
GSM8K (flexible-extract) 69.9%
MMLU (overall) 55.7%
ARC-Challenge (acc_norm) 43.0%
HellaSwag (acc_norm) 60.4%
Winogrande 61.1%
TruthfulQA (mc2) 45.9%
HumanEval (pass@1) 40.2%
MBPP (pass@1) 42.8%

Full benchmark profile

Atomight-V2.5-1.7B full benchmark radar

MMLU breakdown

Category Score
STEM 53.9%
Social Sciences 63.8%
Humanities 48.7%
Other 60.0%

Progress vs. Atomight-V2.1-0.5B

V2.5 (1.7B) is compared here against the previous-generation V2.1 (0.5B) on the benchmarks both models were evaluated on. Note this comparison reflects both the parameter increase (0.5B → 1.7B) and the change in training methodology — it isn't an isolated ablation of either factor alone.

V2.1 vs V2.5 radar comparison

V2.1 vs V2.5 bar comparison

Benchmark V2.1-0.5B V2.5-1.7B Δ
GSM8K (strict) 19.8% 69.6% +49.8
GSM8K (flexible) 32.4% 69.9% +37.5
ARC-Challenge 33.8% 43.0% +9.2
HellaSwag 52.4% 60.4% +8.0

Notably, the gap between GSM8K's strict-match and flexible-extract scores nearly closed between versions (12.6-point gap in V2.1 → 0.3-point gap in V2.5), indicating the GRPO reward shaping improved not just raw math ability but the model's consistency in producing cleanly parseable, correctly formatted answers.

Known Limitations

Word-problem math vs. abstract math. Despite strong GSM8K performance, Atomight-V2.5 underperforms on MMLU's more abstract/formal math and physics subcategories:

Math transfer gap

Category Score
GSM8K (word problems) 69.6%
MMLU College Mathematics 38.0%
MMLU High School Mathematics 35.9%
MMLU College Physics 34.3%
MMLU Abstract Algebra 39.0%

This suggests the training data (competition/olympiad-style word problems) taught strong step-by-step arithmetic reasoning, but that skill did not fully transfer to more abstract, formally-structured mathematics.

Truthfulness. TruthfulQA (45.9%) was not a training target — the model has no specific resistance to plausible-but-false completions beyond what emerges from base pretraining.

Code generalization. HumanEval/MBPP scores (40-43%) are solid for model size but sit below the model's math performance in relative terms, suggesting a similar narrow-transfer pattern to the math gap above.

Training Infrastructure

  • Base model: Qwen/Qwen3-1.7B (post-trained, not a base checkpoint)
  • Method: GRPO via trl, 4-bit QLoRA via Unsloth (r=16, lora_alpha=32)
  • Hardware: Single Google Colab free-tier Tesla T4 (16GB)
  • Memory strategy: Streamed, chunked micro-batches (20 samples/chunk) pulled round-robin across all six datasets, trained, then discarded — avoids materializing multi-million-row datasets in memory
  • Reward functions: XML-format adherence (<thinking>/<answer> tags) + exact-match correctness against verifiable answers

Evaluation Methodology

All scores use standard lm-evaluation-harness task configs at default few-shot settings, with no --limit sampling — results are intended to be directly comparable to other models' published numbers on the same tasks. Code benchmarks (HumanEval, MBPP) were run with HF_ALLOW_CODE_EVAL=1 in a sandboxed Colab runtime.

Citation

If you use this model, please cite the underlying datasets and base model:

Base model: Qwen/Qwen3-1.7B (Qwen Team, Alibaba)
Training datasets: Logics-STEM-SFT-Dataset-Open-5.3M, MegaScience,
OpenMathReasoning, DeepMath-103K, OpenCodeInstruct
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