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arXiv · 2401.13160

SpacTor-T5: Pre-training T5 Models with Span Corruption and Replaced Token Detection

Ke Ye·Heinrich Jiang·Afshin Rostamizadeh·Ayan Chakrabarti·Giulia DeSalvo·Jean-François Kagy·Lazaros Karydas·Gui Citovsky·Sanjiv Kumar
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Abstract

Pre-training large language models is known to be extremely resource intensive and often times inefficient, under-utilizing the information encapsulated in the training text sequences. In this paper, we present SpacTor, a new training procedure consisting of (1) a hybrid objective combining span corruption (SC) and token replacement detection (RTD), and (2) a two-stage curriculum that optimizes the hybrid objective over the initial $\tau$ iterations, then transitions to standard SC loss. We show empirically that the effectiveness of the hybrid objective is tied to the two-stage pre-training schedule, and provide extensive analysis on why this is the case. In our experiments with encoder-decoder architectures (T5) on a variety of NLP tasks, SpacTor-T5 yields the same downstream performance as standard SC pre-training, while enabling a 50% reduction in pre-training iterations and 40% reduction in total FLOPs. Alternatively, given the same amount of computing budget, we find that SpacTor results in significantly improved downstream benchmark performance.

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Ke Ye, Heinrich Jiang, Afshin Rostamizadeh, Ayan Chakrabarti, Giulia DeSalvo, Jean-François Kagy, Lazaros Karydas, Gui Citovsky, Sanjiv Kumar. 2024-01-24. SpacTor-T5: Pre-training T5 Models with Span Corruption and Replaced Token Detection. https://arxiv.org/abs/2401.13160

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