data/graham.txt

Abstract

The dominant sequence transduction models are based on complex recurrent or
convolutional neural networks that include an encoder and a decoder. The best
performing models also connect the encoder and decoder through an attention
mechanism. We propose a new simple network architecture, the Transformer,
based solely on attention mechanisms, dispensing with recurrence and convolutions
entirely. Experiments on two machine translation tasks show these models to
be superior in quality while being more parallelizable and requiring significantly

less time to train. Our model achieves 28.4 BLEU on the WMT 2014 English-
to-German translation task, improving over the existing best results, including

ensembles, by over 2 BLEU. On the WMT 2014 English-to-French translation task,
our model establishes a new single-model state-of-the-art BLEU score of 41.0 after
training for 3.5 days on eight GPUs, a small fraction of the training costs of the
best models from the literature.
1 Introduction
Recurrent neural networks, long short-term memory [12] and gated recurrent [7] neural networks
in particular, have been firmly established as state of the art approaches in sequence modeling and
transduction problems such as language modeling and machine translation [29, 2, 5]. Numerous
efforts have since continued to push the boundaries of recurrent language models and encoder-decoder
architectures [31, 21, 13].
∗Equal contribution. Listing order is random. Jakob proposed replacing RNNs with self-attention and started
the effort to evaluate this idea. Ashish, with Illia, designed and implemented the first Transformer models and
has been crucially involved in every aspect of this work. Noam proposed scaled dot-product attention, multi-head
attention and the parameter-free position representation and became the other person involved in nearly every
detail. Niki designed, implemented, tuned and evaluated countless model variants in our original codebase and
tensor2tensor. Llion also experimented with novel model variants, was responsible for our initial codebase, and
efficient inference and visualizations. Lukasz and Aidan spent countless long days designing various parts of and
implementing tensor2tensor, replacing our earlier codebase, greatly improving results and massively accelerating
our research.
†Work performed while at Google Brain.
‡Work performed while at Google Research.
31st Conference on Neural Information Processing Systems (NIPS 2017), Long Beach, CA, USA.

Recurrent models typically factor computation along the symbol positions of the input and output
sequences. Aligning the positions to steps in computation time, they generate a sequence of hidden
states ht, as a function of the previous hidden state ht−1 and the input for position t. This inherently
sequential nature precludes parallelization within training examples, which becomes critical at longer
sequence lengths, as memory constraints limit batching across examples. Recent work has achieved
significant improvements in computational efficiency through factorization tricks [18] and conditional
computation [26], while also improving model performance in case of the latter. The fundamental
constraint of sequential computation, however, remains.

Attention mechanisms have become an integral part of compelling sequence modeling and transduc-
tion models in various tasks, allowing modeling of dependencies without regard to their distance in

the input or output sequences [2, 16]. In all but a few cases [22], however, such attention mechanisms
are used in conjunction with a recurrent network.
In this work we propose the Transformer, a model architecture eschewing recurrence and instead
relying entirely on an attention mechanism to draw global dependencies between input and output.
The Transformer allows for significantly more parallelization and can reach a new state of the art in
translation quality after being trained for as little as twelve hours on eight P100 GPUs.
2 Background
The goal of reducing sequential computation also forms the foundation of the Extended Neural GPU
[20], ByteNet [15] and ConvS2S [8], all of which use convolutional neural networks as basic building
block, computing hidden representations in parallel for all input and output positions. In these models,
the number of operations required to relate signals from two arbitrary input or output positions grows
in the distance between positions, linearly for ConvS2S and logarithmically for ByteNet. This makes
it more difficult to learn dependencies between distant positions [11]. In the Transformer this is
reduced to a constant number of operations, albeit at the cost of reduced effective resolution due
to averaging attention-weighted positions, an effect we counteract with Multi-Head Attention as
described in section 3.2.
Self-attention, sometimes called intra-attention is an attention mechanism relating different positions
of a single sequence in order to compute a representation of the sequence. Self-attention has been
used successfully in a variety of tasks including reading comprehension, abstractive summarization,
textual entailment and learning task-independent sentence representations [4, 22, 23, 19].

End-to-end memory networks are based on a recurrent attention mechanism instead of sequence-
aligned recurrence and have been shown to perform well on simple-language question answering and

language modeling tasks [28].
To the best of our knowledge, however, the Transformer is the first transduction model relying

entirely on self-attention to compute representations of its input and output without using sequence-
aligned RNNs or convolution. In the following sections, we will describe the Transformer, motivate

self-attention and discuss its advantages over models such as [14, 15] and [8].