Efficiently applying attention to sequential data with the Recurrent Discounted Attention unit

Brendan Maginnis, Pierre Richemond

Abstract:

Recurrent Neural Networks architectures excel at processing sequences by
modelling dependencies over different timescales. The recently introduced
Recurrent Weighted Average (RWA) unit captures long term dependencies
far better than an LSTM on several challenging tasks. The RWA achieves
this by applying attention to each input and computing a weighted average
over the full history of its computations. Unfortunately, the RWA cannot
change the attention it has assigned to previous timesteps, and so struggles
with carrying out consecutive tasks or tasks with changing requirements.
We present the Recurrent Discounted Attention (RDA) unit that builds on
the RWA by additionally allowing the discounting of the past.
We empirically compare our model to RWA, LSTM and GRU units on
several challenging tasks. On tasks with a single output the RWA, RDA and
GRU units learn much quicker than the LSTM and with better performance.
On the multiple sequence copy task our RDA unit learns the task three
times as quickly as the LSTM or GRU units while the RWA fails to learn at
all. On the Wikipedia character prediction task the LSTM performs best
but it followed closely by our RDA unit. Overall our RDA unit performs
well and is sample efficient on a large variety of sequence tasks.

TL;DR: We introduce the Recurrent Discounted Unit which applies attention to any length sequence in linear time

Keywords: RNNs