6,092 research outputs found
Contrastive Difference Predictive Coding
Predicting and reasoning about the future lie at the heart of many
time-series questions. For example, goal-conditioned reinforcement learning can
be viewed as learning representations to predict which states are likely to be
visited in the future. While prior methods have used contrastive predictive
coding to model time series data, learning representations that encode
long-term dependencies usually requires large amounts of data. In this paper,
we introduce a temporal difference version of contrastive predictive coding
that stitches together pieces of different time series data to decrease the
amount of data required to learn predictions of future events. We apply this
representation learning method to derive an off-policy algorithm for
goal-conditioned RL. Experiments demonstrate that, compared with prior RL
methods, ours achieves median improvement in success rates and can
better cope with stochastic environments. In tabular settings, we show that our
method is about more sample efficient than the successor
representation and more sample efficient than the standard (Monte
Carlo) version of contrastive predictive coding.Comment: Website (https://chongyi-zheng.github.io/td_infonce) and code
(https://github.com/chongyi-zheng/td_infonce
An Unsupervised Autoregressive Model for Speech Representation Learning
This paper proposes a novel unsupervised autoregressive neural model for
learning generic speech representations. In contrast to other speech
representation learning methods that aim to remove noise or speaker
variabilities, ours is designed to preserve information for a wide range of
downstream tasks. In addition, the proposed model does not require any phonetic
or word boundary labels, allowing the model to benefit from large quantities of
unlabeled data. Speech representations learned by our model significantly
improve performance on both phone classification and speaker verification over
the surface features and other supervised and unsupervised approaches. Further
analysis shows that different levels of speech information are captured by our
model at different layers. In particular, the lower layers tend to be more
discriminative for speakers, while the upper layers provide more phonetic
content.Comment: Accepted to Interspeech 2019. Code available at:
https://github.com/iamyuanchung/Autoregressive-Predictive-Codin
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