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Addressing Some Limitations of Transformers with Feedback Memory

2020-02-21Code Available1· sign in to hype

Angela Fan, Thibaut Lavril, Edouard Grave, Armand Joulin, Sainbayar Sukhbaatar

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Abstract

Transformers have been successfully applied to sequential, auto-regressive tasks despite being feedforward networks. Unlike recurrent neural networks, Transformers use attention to capture temporal relations while processing input tokens in parallel. While this parallelization makes them computationally efficient, it restricts the model from fully exploiting the sequential nature of the input. The representation at a given layer can only access representations from lower layers, rather than the higher level representations already available. In this work, we propose the Feedback Transformer architecture that exposes all previous representations to all future representations, meaning the lowest representation of the current timestep is formed from the highest-level abstract representation of the past. We demonstrate on a variety of benchmarks in language modeling, machine translation, and reinforcement learning that the increased representation capacity can create small, shallow models with much stronger performance than comparable Transformers.

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Benchmark Results

DatasetModelMetricClaimedVerifiedStatus
enwik8Feedback TransformerBit per Character (BPC)0.96Unverified
Penn Treebank (Character Level)Feedback TransformerBit per Character (BPC)1.16Unverified
WikiText-103Feedback Transformer (8 layers)Test perplexity18.2Unverified
WikiText-103Feedback Transformer (4 layers)Test perplexity22.4Unverified

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