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70 lines
2.4 KiB
ReStructuredText
70 lines
2.4 KiB
ReStructuredText
Transformer XL
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The Transformer-XL model was proposed in
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`Transformer-XL: Attentive Language Models Beyond a Fixed-Length Context`_
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by Zihang Dai*, Zhilin Yang*, Yiming Yang, Jaime Carbonell, Quoc V. Le, Ruslan Salakhutdinov.
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It's a causal (uni-directional) transformer with relative positioning (sinusoïdal) embeddings which can reuse
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previously computed hidden-states to attend to longer context (memory).
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This model also uses adaptive softmax inputs and outputs (tied).
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The abstract from the paper is the following:
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*Transformers have a potential of learning longer-term dependency, but are limited by a fixed-length context in the
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setting of language modeling. We propose a novel neural architecture Transformer-XL that enables learning dependency
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beyond a fixed length without disrupting temporal coherence. It consists of a segment-level recurrence mechanism and
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a novel positional encoding scheme. Our method not only enables capturing longer-term dependency, but also resolves
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the context fragmentation problem. As a result, Transformer-XL learns dependency that is 80% longer than RNNs and
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450% longer than vanilla Transformers, achieves better performance on both short and long sequences, and is up
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to 1,800+ times faster than vanilla Transformers during evaluation. Notably, we improve the state-of-the-art results
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of bpc/perplexity to 0.99 on enwiki8, 1.08 on text8, 18.3 on WikiText-103, 21.8 on One Billion Word, and 54.5 on
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Penn Treebank (without finetuning). When trained only on WikiText-103, Transformer-XL manages to generate reasonably
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coherent, novel text articles with thousands of tokens.*
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Tips:
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- Transformer-XL uses relative sinusoidal positional embeddings so it's usually advised to pad the inputs on
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the left rather than the right.
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``TransfoXLConfig``
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~~~~~~~~~~~~~~~~~~~~~
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.. autoclass:: transformers.TransfoXLConfig
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:members:
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``TransfoXLTokenizer``
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~~~~~~~~~~~~~~~~~~~~~~~~~~
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.. autoclass:: transformers.TransfoXLTokenizer
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:members:
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``TransfoXLModel``
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~~~~~~~~~~~~~~~~~~~~~~~~~~
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.. autoclass:: transformers.TransfoXLModel
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:members:
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``TransfoXLLMHeadModel``
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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.. autoclass:: transformers.TransfoXLLMHeadModel
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:members:
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``TFTransfoXLModel``
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~~~~~~~~~~~~~~~~~~~~~~~~~~
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.. autoclass:: transformers.TFTransfoXLModel
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:members:
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``TFTransfoXLLMHeadModel``
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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.. autoclass:: transformers.TFTransfoXLLMHeadModel
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:members:
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