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Hummingbird-V2

Hummingbird-V2 is a 9.6M-parameter English base language model trained from scratch on 10 billion tokens. It is designed for text completion and continuation scoring.

Model series

Hummingbird-V2 follows Hummingbird-V1 in the same small language model series. V2 was trained from a fresh initialization.

Architecture

Property Value
Parameters 9,592,720
Layers / hidden size 14 / 240
Vocabulary 4,096-token digit-aware byte-level BPE
Maximum context 2,048 tokens
Architecture Decoder-only Transformer with grouped-query attention and SwiGLU

Training and data

The model was trained on this balanced mix:

Source Share
FineWeb-Edu sources 55%
Cosmopedia v2 15%
FineMath 4+ 10%
DCLM baseline 10%
Dolma 3 science, question answering, and code 7%
FinePDFs-Edu 3%

Training used Muon and AdamW with a 512-token context. See training data for source details and training provenance for the full recipe.

Zero-shot evaluation

Author-run zero-shot results for the 10B-token checkpoint. Task scores are normalized continuation accuracy in percent; the Intelligence Index is a chance-normalized composite.

Benchmark Score
HellaSwag 27.63
ARC-Easy 39.39
ARC-Challenge 21.16
PIQA 57.40
ArithMark-3 36.00
Chance-normalized Intelligence Index 9.556

These evaluations helped select the released checkpoint; results have not been independently verified.

Use

Load juinron/Hummingbird-V2 with Transformers and the packaged custom code:

import torch
from transformers import AutoModelForCausalLM, AutoTokenizer

model_id = "juinron/Hummingbird-V2"
tokenizer = AutoTokenizer.from_pretrained(model_id, trust_remote_code=True)
model = AutoModelForCausalLM.from_pretrained(model_id, trust_remote_code=True).eval()

inputs = tokenizer("The color of the sky is", return_tensors="pt")
with torch.inference_mode():
    output = model.generate(**inputs, max_new_tokens=32, do_sample=False, use_cache=False)
print(tokenizer.decode(output[0], skip_special_tokens=True))

trust_remote_code=True loads the packaged model code. Review it before use.

Limitations

Hummingbird-V2 is small and English-focused. It can make factual or reasoning errors and is not instruction-tuned or safety-aligned. Do not rely on it for consequential decisions.

License

The model package is released under Apache-2.0. Third-party dataset notices are included in NOTICE and TRAINING_DATA.md.

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