Funnel-Transformer: Filtering out Sequential Redundancy for Efficient Language Processing

Introduction

Funnel-Transformer is a new self-attention model that gradually compresses the sequence of hidden states to a shorter one and hence reduces the computation cost. More importantly, by re-investing the saved FLOPs from length reduction in constructing a deeper or wider model, Funnel-Transformer usually has a higher capacity given the same FLOPs. In addition, with a decoder, Funnel-Transformer is able to recover the token-level deep representation for each token from the reduced hidden sequence, which enables standard pretraining.

For a detailed description of technical details and experimental results, please refer to our paper:

Funnel-Transformer: Filtering out Sequential Redundancy for Efficient Language Processing

Zihang Dai*, Guokun Lai*, Yiming Yang, Quoc V. Le

(*: equal contribution)

Preprint 2020

Source Code

Data Download

• The corresponding source code and instructions are in the data-scrips folder, which specifies how to access the raw data we used in this work.

TensorFlow

• The corresponding source code is in the tensorflow folder, which was developed and exactly used for TPU pretraining & finetuning as presented in the paper.
• The TensorFlow funetuning code mainly supports TPU finetuining on GLUE benchmark, text classification, SQuAD and RACE.
• Please refer to tensorflow/README.md for details.

PyTorch

• The source code is in the pytorch folder, which only serves as an example PyTorch implementation of Funnel-Transformer.
• Hence, the PyTorch code only supports GPU finetuning for the GLUE benchmark & text classification.
• Please refer to pytorch/README.md for details.

Pretrained models

Each .tar.gz file contains three items:

• A TensorFlow or PyTorch checkpoint (model.ckpt-* or model.ckpt.pt) checkpoint containing the pre-trained weights (Note: The TensorFlow checkpoint actually corresponds to 3 files).
• A Word Piece model (vocab.uncased.txt) used for (de)tokenization.
• A config file (net_config.json or net_config.pytorch.json) which specifies the hyperparameters of the model.

You also can use download_all_ckpts.sh to download all checkpoints mentioned above.

For how to use the pretrained models, please refer to tensorflow/README.md or pytorch/README.md respectively.

Results