Highlights
- Distilled chain-of-thought — every answer opens with a
<think> block learned directly from Qwen3.8 2.4T A95B traces rather than synthetic self-generated reasoning.
- 4B weight class — bf16 fits in ~8 GB; quantized builds run on laptops and consumer GPUs.
- Native function calling per Qwen3.5's specification — no wrapper or tool-specific fine-tune required.
- 262,144-token native context, inherited from the Qwen3.5 base.
- Full fine-tune — every parameter updated; not an adapter.
Model Overview
- Type: Causal Language Model (text path of a vision-language base)
- Base: Qwen/Qwen3.5-4B
- Number of Parameters: 4B
- Training: SFT (off-policy distillation) on ~45,000 teacher traces
- Teacher: Qwen3.8 2.4T A95B (internal distillation datasets)
- Context Length: 262,144 natively
Benchmark Results
Measured with lm-evaluation-harness, HF backend, identical settings for base and student. Both models are reasoning models and are evaluated with the CoT protocols (gsm8k_cot, mmlu_flan_cot_zeroshot); MMLU covers all 57 subjects (~1,700 questions). Flexible-extract is the primary metric; strict-match requires exact answer formatting.
Table with columns: Task, Metric, Qwen3.5-4B (base), Qwen3.8-4B, Δ| Task | Metric | Qwen3.5-4B (base) | Qwen3.8-4B | Δ |
|---|
| gsm8k_cot | exact_match (flexible) | 0.850 | 0.785 | −0.065 |
| gsm8k_cot | exact_match (strict) | 0.850 | 0.785 | −0.065 |
| mmlu (CoT, 57 subjects) | acc (flexible-extract) | 0.354 | 0.553 | |
Sampling for generation: temperature=0.6, top_p=0.95, top_k=20 (Qwen3.5 recommended settings).
Quickstart
from transformers import AutoModelForCausalLM, AutoTokenizer
import torch
model_id = "empero-ai/Qwen3.8-4B"
tok = AutoTokenizer.from_pretrained(model_id)
model = AutoModelForCausalLM.from_pretrained(model_id, dtype=torch.bfloat16, device_map="auto")
messages = [{"role": "user", "content": "A snail is at the bottom of a 10-meter well. Each day it climbs 3 meters, each night it slips back 2. How many days until it escapes?"}]
inputs = tok.apply_chat_template(messages, add_generation_prompt=True, return_tensors="pt").to(model.device)
out = model.generate(inputs, max_new_tokens=16384,
temperature=0.6, top_p=0.95, top_k=20, do_sample=True)
print(tok.decode(out[0][inputs.shape[1]:], skip_special_tokens=True))
A recent transformers release with Qwen3.5 support is required, along with the Gated DeltaNet kernels (flash-linear-attention and a CUDA-matched causal_conv1d build) — without them the linear-attention layers fall back to slow, memory-hungry PyTorch ops.
Best Practices
- Sampling:
temperature=0.6, top_p=0.95, top_k=20. Greedy decoding on long generations is a known repetition-loop failure mode for reasoning models in this class.
- Output length: allow generous
max_new_tokens (16,384 recommended); every answer opens with a <think> block. Parse and strip the <think>...</think> span for end users.
- Scope: the trace mix emphasizes mathematics, reasoning, and instruction following; for the strongest code performance in the family, use Qwen3.8-9B. The fine-tune is text-only; vision behavior is inherited from the base and was not evaluated here.
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Support / Donate
If this model helped you, consider supporting the project:
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Provenance & licensing
Weights are released under Apache-2.0, inherited from the Qwen3.5-4B base. Shared for research and experimentation, as-is.
Acknowledgements