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1. Verfasser: Wang, Zhengxiang
Format: Preprint
Veröffentlicht: 2023
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Online-Zugang:https://arxiv.org/abs/2303.06841
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author Wang, Zhengxiang
author_facet Wang, Zhengxiang
contents The paper studies the capabilities of Recurrent-Neural-Network sequence to sequence (RNN seq2seq) models in learning four transduction tasks: identity, reversal, total reduplication, and quadratic copying. These transductions are traditionally well studied under finite state transducers and attributed with increasing complexity. We find that RNN seq2seq models are only able to approximate a mapping that fits the training or in-distribution data, instead of learning the underlying functions. Although attention makes learning more efficient and robust, it does not overcome the out-of-distribution generalization limitation. We establish a novel complexity hierarchy for learning the four tasks for attention-less RNN seq2seq models, which may be understood in terms of the complexity hierarchy of formal languages, instead of string transductions. RNN variants also play a role in the results. In particular, we show that Simple RNN seq2seq models cannot count the input length.
format Preprint
id arxiv_https___arxiv_org_abs_2303_06841
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle Learning Transductions and Alignments with RNN Seq2seq Models
Wang, Zhengxiang
Computation and Language
The paper studies the capabilities of Recurrent-Neural-Network sequence to sequence (RNN seq2seq) models in learning four transduction tasks: identity, reversal, total reduplication, and quadratic copying. These transductions are traditionally well studied under finite state transducers and attributed with increasing complexity. We find that RNN seq2seq models are only able to approximate a mapping that fits the training or in-distribution data, instead of learning the underlying functions. Although attention makes learning more efficient and robust, it does not overcome the out-of-distribution generalization limitation. We establish a novel complexity hierarchy for learning the four tasks for attention-less RNN seq2seq models, which may be understood in terms of the complexity hierarchy of formal languages, instead of string transductions. RNN variants also play a role in the results. In particular, we show that Simple RNN seq2seq models cannot count the input length.
title Learning Transductions and Alignments with RNN Seq2seq Models
topic Computation and Language
url https://arxiv.org/abs/2303.06841