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Flan-UL2

GoogleOpen WeightsPending Human Review

Flan-UL2 is the independently released instruction-tuned UL2 update. Continued training extends the receptive field to 2048 tokens and removes the requirement for mode-switch tokens before Flan instruction tuning. The 20B T5-style encoder-decoder supports text-to-text generation, reasoning, and few-shot prompting. Google’s UL2 repository records checkpoint release on February 28, 2023, before later model-card and ecosystem announcements.

2023-02-28
20B
T5-style encoder-decoder Transformer with continued UL2 pretraining and Flan instruction fine-tuning
Apache-2.0

Specifications

Parameters
20B
Architecture
T5-style encoder-decoder Transformer with continued UL2 pretraining and Flan instruction fine-tuning
License
Apache-2.0
Context Window
2,048 tokens
Type
text
Modalities
text

Benchmark Scores

Advanced Specifications

Model Family
UL2
Finetuned From
ul2
API Access
Not Available
Chat Interface
Not Available
Hardware Support
GPUTPUCPU

Capabilities & Limitations

Capabilities
instruction followingtext-to-text generationreasoningfew-shot learning
Known Limitations
The 2048-token receptive field is short relative to modern long-context models.Reasoning answers can be incorrect and need verification.
Notable Use Cases
NLP researchreasoning experimentstext-task adaptation

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