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--- |
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language: |
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- nl |
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- en |
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- multilingual |
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license: apache-2.0 |
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tags: |
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- dutch |
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- english |
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- t5 |
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- t5x |
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- ul2 |
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- seq2seq |
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datasets: |
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- yhavinga/mc4_nl_cleaned |
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- yhavinga/nedd_wiki_news |
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inference: false |
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--- |
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# ul2-large-dutch-english for Dutch and English |
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Pretrained T5 model on Dutch and English using a UL2 (Mixture-of-Denoisers) objective. |
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The T5 model was introduced in |
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[this paper](https://arxiv.org/abs/1910.10683) |
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and first released at [this page](https://github.com/google-research/text-to-text-transfer-transformer). |
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The UL2 objective was introduced in |
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[this paper](https://arxiv.org/abs/2205.05131) |
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and first released at [this page](https://github.com/google-research/google-research/tree/master/ul2). |
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**Note:** The Hugging Face inference widget is deactivated because this model needs a text-to-text fine-tuning on |
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a specific downstream task to be useful in practice. |
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## Model description |
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T5 is an encoder-decoder model and treats all NLP problems in a text-to-text format. |
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`ul2-large-dutch-english` T5 is a transformers model pretrained on a very large corpus of |
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Dutch and English data in a self-supervised fashion. |
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This means it was pretrained on the raw texts only, with no humans labelling them in any way |
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(which is why it can use lots of publicly available data) with an automatic process to generate |
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inputs and outputs from those texts. |
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This model used the [T5 v1.1](https://github.com/google-research/text-to-text-transfer-transformer/blob/main/released_checkpoints.md#t511) improvements compared to the original T5 model during the pretraining: |
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- GEGLU activation in the feed-forward hidden layer, rather than ReLU - see [here](https://arxiv.org/abs/2002.05202) |
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- Dropout was turned off during pre-training. Dropout should be re-enabled during fine-tuning |
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- Pre-trained on self-supervised objective only without mixing in the downstream tasks |
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- No parameter sharing between embedding and classifier layer |
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### UL2 pretraining objective |
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This model was pretrained with the UL2's Mixture-of-Denoisers (MoD) objective, that combines diverse pre-training |
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paradigms together. UL2 frames different objective functions for training language models as denoising tasks, where |
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the model has to recover missing sub-sequences of a given input. During pre-training it uses a novel mixture-of-denoisers |
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that samples from a varied set of such objectives, each with different configurations. UL2 is trained using a mixture of |
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three denoising tasks: |
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1. R-denoising (or regular span corruption), which emulates the standard T5 span corruption objective; |
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2. X-denoising (or extreme span corruption); and |
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3. S-denoising (or sequential PrefixLM). |
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During pre-training, we sample from the available denoising tasks based on user-specified ratios. |
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UL2 introduces a notion of mode switching, wherein downstream fine-tuning is associated with specific pre-training |
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denoising task. During the pre-training, a paradigm token is inserted to the input |
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(`[NLU]` for R-denoising, `[NLG]` for X-denoising, or `[S2S]` for S-denoising) indicating the denoising task at hand. |
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Then, during fine-tuning the same input token should be inserted to get the best performance for different downstream |
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fine-tuning tasks. |
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## Intended uses & limitations |
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This model was only pretrained in a self-supervised way excluding any supervised training. |
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Therefore, this model has to be fine-tuned before it is usable on a downstream task, |
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like text classification, unlike the Google's original T5 model. |
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**Note:** You most likely need to fine-tune these T5/UL2 models without mixed precision |
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so fine-tune them with full fp32 precision. Fine-tuning with Flax in bf16 - `model.to_bf16()` - is possible |
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if you set the mask correctly to exclude layernorm and embedding layers. Also note that the T5x pre-training |
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and fine-tuning configs set `z_loss` to 1e-4, which is used to keep the loss scale from underflowing. |
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You can also find more fine-tuning tips from [here](https://discuss.huggingface.co/t/t5-finetuning-tips), for example. |
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**Note**: For fine-tuning, most likely you can get better results if you insert a prefix token |
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of `[NLU]`, `[NLG]`, or `[S2S]` to your input texts. |
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For general language understanding fine-tuning tasks, you could use the `[NLU]` token. |
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For GPT-style causal language generation, you could use the `[S2S]` token. |
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The token `[NLG]` of the X-denoising pretrain task is somewhat mix between the language understanding and causal language |
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generation so the token `[NLG]` could maybe be used for language generation fine-tuning too. |
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### How to use |
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Here is how to use this model in PyTorch: |
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```python |
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from transformers import T5Tokenizer, T5ForConditionalGeneration |
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tokenizer = T5Tokenizer.from_pretrained("yhavinga/ul2-large-dutch-english", use_fast=False) |
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model = T5ForConditionalGeneration.from_pretrained("yhavinga/ul2-large-dutch-english") |
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``` |
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and in Flax: |
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```python |
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from transformers import T5Tokenizer, FlaxT5ForConditionalGeneration |
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tokenizer = T5Tokenizer.from_pretrained("yhavinga/ul2-large-dutch-english", use_fast=False) |
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model = FlaxT5ForConditionalGeneration.from_pretrained("yhavinga/ul2-large-dutch-english") |
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``` |
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### Limitations and bias |
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The training data used for this model contains a lot of unfiltered content from the internet, which is far from neutral. |
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Therefore, the model can have biased predictions. This bias will also affect all fine-tuned versions of this model. |
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## Training data |
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The `ul2-large-dutch-english` T5 model was pre-trained simultaneously on a combination of several datasets, |
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including the `full_en_nl` config of the "mc4_nl_cleaned" dataset, which is a cleaned version of Common Crawl's web |
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crawl corpus, Dutch books, the Dutch subset of Wikipedia (2022-03-20), the English subset of Wikipedia (2022-03-01), |
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and a subset of "mc4_nl_cleaned" |
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containing only texts from Dutch newspapers. |
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## Training procedure |
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### Preprocessing |
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The ul2-large-dutch-english T5 model uses a SentencePiece unigram tokenizer with a vocabulary of 32,000 tokens. |
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The tokenizer includes the special tokens `<pad>`, `</s>`, `<unk>`, known from the original T5 paper, |
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`[NLU]`, `[NLG]` and `[S2S]` for the MoD pre-training, and `<n>` for newline. |
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During pre-training with the UL2 objective, input and output sequences consist of 512 consecutive tokens. |
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The tokenizer does not lowercase texts and is therefore case-sensitive; it distinguises |
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between `dutch` and `Dutch`. |
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Additionally, 100+28 extra tokens were added for pre-training tasks, resulting in a total of 32,128 tokens. |
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### Pretraining |
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The model was trained on TPUv3-8 VM, sponsored by the [Google TPU Research Cloud](https://sites.research.google/trc/about/), |
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for 2650000 steps with a batch size of 64 |
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(in total 84B tokens). |
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The optimizer used was AdaFactor with learning rate warmup for 10K steps with a constant learning rate of 1e-2, |
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and then an inverse square root decay (exponential decay) of the learning rate after. |
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The model was trained with Google's Jax/Flax based [t5x framework](https://github.com/google-research/t5x) with help |
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from [Stephenn Fernandes](https://huggingface.co/StephennFernandes) to get started writing task definitions that wrap |
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HF datasets. |
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The UL2 training objective code used with the [t5x framework](https://github.com/google-research/t5x) was copied and |
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slightly modified from the [UL2 paper](https://arxiv.org/pdf/2205.05131.pdf) appendix chapter 9.2 by the authors |
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of the Finnish ul2 models. Used UL2 objective code is available in the repository |
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[Finnish-NLP/ul2-base-nl36-finnish](https://huggingface.co/Finnish-NLP/ul2-base-nl36-finnish) in the files `ul2_objective.py` and `tasks.py`. |
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UL2's mixture-of-denoisers configuration was otherwise equal to the UL2 paper |
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but for the rate of mixing denoisers, 20% for S-denoising was used (suggested at the paper chapter 4.5) |
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and the rest was divided equally between the R-denoising and X-denoising (i.e. 40% for both). |
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### Model list |
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Models in this series: |
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| | ul2-base-dutch-english | ul2-large-dutch-english | ul2-small-dutch-english | |
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|:---------------------|:-------------------------|:--------------------------|:--------------------------| |
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| model_type | t5 | t5 | t5 | |
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| _pipeline_tag | text2text-generation | text2text-generation | text2text-generation | |
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| d_model | 768 | 1024 | 512 | |
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| d_ff | 2048 | 2816 | 1024 | |
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| num_heads | 12 | 16 | 6 | |
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| d_kv | 64 | 64 | 64 | |
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| num_layers | 12 | 24 | 8 | |
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| num_decoder_layers | 12 | 24 | 8 | |
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| feed_forward_proj | gated-gelu | gated-gelu | gated-gelu | |
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| dense_act_fn | gelu_new | gelu_new | gelu_new | |
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| vocab_size | 32128 | 32128 | 32128 | |
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| tie_word_embeddings | 0 | 0 | 0 | |
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| torch_dtype | float32 | float32 | float32 | |
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| _gin_batch_size | 128 | 64 | 128 | |
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| _gin_z_loss | 0.0001 | 0.0001 | 0.0001 | |
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| _gin_t5_config_dtype | 'bfloat16' | 'bfloat16' | 'bfloat16' | |
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## Evaluation results |
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See the evaluation section in the interactive [Pre-training Dutch T5 Models](https://huggingface.co/spaces/yhavinga/pre-training-dutch-t5-models) blog. |
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## Acknowledgements |
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This project would not have been possible without compute generously provided by Google through the |
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[TPU Research Cloud](https://sites.research.google/trc/). |
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Thanks to the [Finnish-NLP](https://huggingface.co/Finnish-NLP) authors for releasing their code for the UL2 objective and associated task definitions. |
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Thanks to [Stephenn Fernandes](https://huggingface.co/StephennFernandes) for helping me get started with the t5x framework. |
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Created by [Yeb Havinga](https://www.linkedin.com/in/yeb-havinga-86530825/) |
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