Model: Mercity/Qwen3-8B-LaCo-Pruned Source: Original Platform
license, base_model, arvix, tags, library_name, pipeline_tag, language, datasets, model-index
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| apache-2.0 | Qwen/Qwen3-8B-Base | arxiv:2507.02279 |
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transformers | text-generation |
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Qwen3-8B-LaCo-Pruned
This model is a layer-pruned version of Qwen3-8B-Base using the LaCo (Layer Collapse) structured pruning method.
Model Summary
| Attribute | Value |
|---|---|
| Base Model | Qwen/Qwen3-8B-Base |
| Pruning Method | LaCo (Layer Collapse) |
| Original Layers | 36 |
| Pruned Layers | 26 |
| Layers Removed | 10 |
| Compression | 27.8% |
| Parameters | ~5.8B (reduced from ~8B) |
Intended Use
- Research on model compression and efficiency
- Fine-tuning base for domain-specific applications
- Inference optimization where speed/memory matters more than factual accuracy
- Edge deployment scenarios with limited computational resources
⚠️ Important Limitations
This pruned model has significantly reduced factual knowledge capabilities. It performs at near-random levels on knowledge-intensive benchmarks like MMLU.
| Use Case | Status |
|---|---|
| Physical reasoning tasks | ✅ Good (82.6% retained) |
| Reading comprehension | ⚠️ Acceptable (74.3% retained) |
| Common sense reasoning | ⚠️ Degraded (61.8% retained) |
| Factual question answering | ❌ Not recommended |
| Knowledge-intensive tasks | ❌ Not recommended |
Recommendation: Fine-tune this model on your target domain before deployment.
Pruning Details
LaCo Hyperparameters
| Parameter | Value | Description |
|---|---|---|
| MERGE_LAYERS (C) | 3 | Layers merged per operation |
| LOWEST_LAY (L) | 4 | Minimum layer index for merging |
| HIGHEST_LAY (H) | 28 | Maximum layer index for merging |
| INTERVAL (I) | 2 | Minimum gap between merge points |
| THRESHOLD (T) | 0.85 | Cosine similarity threshold |
| MAX_COMPRESSION | 30% | Maximum allowed compression |
Pruning Statistics
| Metric | Value |
|---|---|
| Successful Merges | 5 |
| Rejected Merges | 0 |
| Total Iterations | 6 |
| Final Compression | 27.8% |
Hidden State Similarity (Calibration Set)
| Metric | Value |
|---|---|
| Average | 0.9680 |
| Min | 0.9492 |
| Max | 0.9766 |
Individual similarities: [0.9492, 0.9727, 0.9609, 0.9766, 0.9688, 0.9648, 0.9648, 0.9766, 0.9727, 0.9727]
Perplexity Results
| Model | Perplexity | Ratio |
|---|---|---|
| Original (Qwen3-8B-Base) | 26.19 | 1.00× |
| Pruned (this model) | 71.48 | 2.73× |
Benchmark Results
Comparison with Original Qwen3-8B-Base
| Benchmark | Original | Pruned | Retention | Status |
|---|---|---|---|---|
| PIQA | 79.54% | 65.67% | 82.6% | ✅ Good |
| BoolQ | 83.09% | 61.77% | 74.3% | ⚠️ Acceptable |
| HellaSwag | 78.55% | 48.52% | 61.8% | ⚠️ Degraded |
| MMLU (5-shot) | 76.89% | 25.12% | 32.7% | ❌ Near random |
Original scores from Qwen3 Technical Report
Key Findings
- Physical reasoning preserved: PIQA retained 82.6% of original performance
- Factual knowledge destroyed: MMLU collapsed to random-chance (25% for 4-way MCQ)
- Perplexity underestimates damage: 2.73× PPL ratio doesn't predict the benchmark collapse
- Layer-specific knowledge: Factual knowledge appears encoded in specific removed layers
Usage
Basic Inference
from transformers import AutoModelForCausalLM, AutoTokenizer
model_name = "Mercity/Qwen3-8B-LaCo-Pruned"
tokenizer = AutoTokenizer.from_pretrained(model_name, trust_remote_code=True)
model = AutoModelForCausalLM.from_pretrained(
model_name,
torch_dtype="auto",
device_map="auto",
trust_remote_code=True
)
# Text generation
prompt = "The process of photosynthesis"
inputs = tokenizer(prompt, return_tensors="pt").to(model.device)
outputs = model.generate(**inputs, max_new_tokens=100, do_sample=True, temperature=0.7)
print(tokenizer.decode(outputs[0], skip_special_tokens=True))
With 4-bit Quantization (Further Compression)
from transformers import AutoModelForCausalLM, AutoTokenizer, BitsAndBytesConfig
quantization_config = BitsAndBytesConfig(
load_in_4bit=True,
bnb_4bit_compute_dtype="float16",
bnb_4bit_quant_type="nf4",
)
model = AutoModelForCausalLM.from_pretrained(
"Mercity/Qwen3-8B-LaCo-Pruned",
quantization_config=quantization_config,
device_map="auto",
trust_remote_code=True
)
Recovery Recommendations
To restore performance after pruning:
Option 1: LoRA Fine-tuning (Recommended)
from peft import LoraConfig, get_peft_model
lora_config = LoraConfig(
r=32,
lora_alpha=64,
target_modules=["q_proj", "k_proj", "v_proj", "o_proj",
"gate_proj", "up_proj", "down_proj"],
lora_dropout=0.05,
)
model = get_peft_model(model, lora_config)
# Fine-tune on OpenOrca, Alpaca, or domain-specific data
Option 2: Knowledge Distillation
Use original Qwen3-8B-Base as teacher to transfer knowledge back.
Expected Recovery
- With fine-tuning: +15-25% on MMLU
- With knowledge distillation: +25-35% on MMLU
Technical Specifications
| Attribute | Value |
|---|---|
| Architecture | Transformer decoder-only |
| Parameters | ~5.8B |
| Layers | 26 |
| Hidden Size | 4096 |
| Attention Heads (Q) | 32 |
| Attention Heads (KV) | 8 (GQA) |
| Intermediate Size | 12288 |
| Vocabulary Size | 151,669 |
| Max Context Length | 32,768 tokens |
| Precision | bfloat16 |
Citation
If you use this model, please cite the original LaCo paper and Qwen3:
@article{yang2024laco,
title={LaCo: Large Language Model Pruning via Layer Collapse},
author={Yang, Yifei and Cao, Zouying and Zhao, Hai},
journal={arXiv preprint arXiv:2402.11187},
year={2024}
}
@misc{qwen3technicalreport,
title={Qwen3 Technical Report},
author={Qwen Team},
year={2025},
eprint={2505.09388},
archivePrefix={arXiv},
primaryClass={cs.CL},
url={https://arxiv.org/abs/2505.09388}
}
References
License
Apache 2.0 (same as base Qwen3 model)
Acknowledgments
- Qwen Team for the excellent Qwen3-8B-Base model
- LaCo authors for the pruning methodology
- Hugging Face for model hosting
Description
Languages
Jinja
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