README.md

---
license: cc-by-nc-sa-4.0
pipeline_tag: fill-mask
language: en
tags:
- long_documents
datasets:
- c4
model-index:
- name: kiddothe2b/hierarchical-transformer-base-4096
  results: []
---

# Hierarchical Attention Transformer (HAT) / hierarchical-transformer-base-4096

## Model description

This is a Hierarchical Attention Transformer (HAT) model as presented in [An Exploration of Hierarchical Attention Transformers for Efficient Long Document Classification (Chalkidis et al., 2022)](https://arxiv.org/abs/xxx). 

The model has been warm-started re-using the weights of RoBERTa [(Liu et al., 2019)](https://arxiv.org/abs/1907.11692), and continued pre-trained for MLM in long sequences following the paradigm of Longformer released by [Beltagy et al. (2020)](https://arxiv.org/abs/2004.05150). It supports sequences of length up to 4,096.

HAT use a hierarchical attention, which is a combination of segment-wise and cross-segment attention operations. You can think segments as paragraphs or sentences.

## Intended uses & limitations

You can use the raw model for masked language modeling, but it's mostly intended to be fine-tuned on a downstream task.
See the [model hub](https://huggingface.co/models?filter=hierarchical-transformer) to look for fine-tuned versions on a task that
interests you.

Note that this model is primarily aimed at being fine-tuned on tasks that use the whole document to make decisions, such as document classification, sequential sentence classification or question answering.

## How to use

You can use this model directly with a pipeline for masked language modeling:

```python
from transformers import pipeline
mlm_model = pipeline('fill-mask', model='kiddothe2b/hierarchical-transformer-base-4096', trust_remote_code=True)
mlm_model("Hello I'm a <mask> model.")
```

You can also fine-tun it for SequenceClassification, SequentialSentenceClassification, and MultipleChoice down-stream tasks:

```python
from transformers import AutoTokenizer, AutoModelforSequenceClassification
tokenizer = AutoTokenizer.from_pretrained("kiddothe2b/hierarchical-transformer-base-4096", trust_remote_code=True)
doc_classifier = AutoModelforSequenceClassification(model='kiddothe2b/hierarchical-transformer-base-4096', trust_remote_code=True)
```

## Limitations and bias

The training data used for this model contains a lot of unfiltered content from the internet, which is far from
neutral. Therefore, the model can have biased predictions.


## Training procedure

### Training and evaluation data

The model has been warm-started from [roberta-base](https://huggingface.co/roberta-base) checkpoint and has been continued pre-trained for additional 50k steps in long sequences (> 1024 subwords) of [C4](https://huggingface.co/datasets/c4) (Raffel et al., 2020).


### Training hyperparameters

The following hyperparameters were used during training:
- learning_rate: 0.0001
- train_batch_size: 2
- eval_batch_size: 2
- seed: 42
- distributed_type: tpu
- num_devices: 8
- gradient_accumulation_steps: 8
- total_train_batch_size: 128
- total_eval_batch_size: 16
- optimizer: Adam with betas=(0.9,0.999) and epsilon=1e-08
- lr_scheduler_type: linear
- lr_scheduler_warmup_ratio: 0.1
- training_steps: 50000

### Training results

| Training Loss | Epoch | Step  | Validation Loss |
|:-------------:|:-----:|:-----:|:---------------:|
| 1.7437        | 0.2   | 10000 | 1.6370          |
| 1.6994        | 0.4   | 20000 | 1.6054          |
| 1.6726        | 0.6   | 30000 | 1.5718          |
| 1.644         | 0.8   | 40000 | 1.5526          |
| 1.6299        | 1.0   | 50000 | 1.5368          |


### Framework versions

- Transformers 4.19.0.dev0
- Pytorch 1.11.0+cu102
- Datasets 2.0.0
- Tokenizers 0.11.6


##Citing
If you use HAT in your research, please cite [An Exploration of Hierarchical Attention Transformers for Efficient Long Document Classification](https://arxiv.org/abs/xxx)

```
@misc{chalkidis-etal-2022-hat,
  url = {https://arxiv.org/abs/xxx},
  author = {Chalkidis, Ilias and Dai, Xiang and Fergadiotis, Manos and Malakasiotis, Prodromos and Elliott, Desmond},
  title = {An Exploration of Hierarchical Attention Transformers for Efficient Long Document Classification},
  publisher = {arXiv},
  year = {2022},
}
```