Tatsuya Aoki


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Generic Mechanism for Reducing Repetitions in Encoder-Decoder Models
Ying Zhang | Hidetaka Kamigaito | Tatsuya Aoki | Hiroya Takamura | Manabu Okumura
Proceedings of the International Conference on Recent Advances in Natural Language Processing (RANLP 2021)

Encoder-decoder models have been commonly used for many tasks such as machine translation and response generation. As previous research reported, these models suffer from generating redundant repetition. In this research, we propose a new mechanism for encoder-decoder models that estimates the semantic difference of a source sentence before and after being fed into the encoder-decoder model to capture the consistency between two sides. This mechanism helps reduce repeatedly generated tokens for a variety of tasks. Evaluation results on publicly available machine translation and response generation datasets demonstrate the effectiveness of our proposal.


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Neural text normalization leveraging similarities of strings and sounds
Riku Kawamura | Tatsuya Aoki | Hidetaka Kamigaito | Hiroya Takamura | Manabu Okumura
Proceedings of the 28th International Conference on Computational Linguistics

We propose neural models that can normalize text by considering the similarities of word strings and sounds. We experimentally compared a model that considers the similarities of both word strings and sounds, a model that considers only the similarity of word strings or of sounds, and a model without the similarities as a baseline. Results showed that leveraging the word string similarity succeeded in dealing with misspellings and abbreviations, and taking into account the sound similarity succeeded in dealing with phonetic substitutions and emphasized characters. So that the proposed models achieved higher F1 scores than the baseline.


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Controlling Contents in Data-to-Document Generation with Human-Designed Topic Labels
Kasumi Aoki | Akira Miyazawa | Tatsuya Ishigaki | Tatsuya Aoki | Hiroshi Noji | Keiichi Goshima | Ichiro Kobayashi | Hiroya Takamura | Yusuke Miyao
Proceedings of the 12th International Conference on Natural Language Generation

We propose a data-to-document generator that can easily control the contents of output texts based on a neural language model. Conventional data-to-text model is useful when a reader seeks a global summary of data because it has only to describe an important part that has been extracted beforehand. However, because depending on users, it differs what they are interested in, so it is necessary to develop a method to generate various summaries according to users’ interests. We develop a model to generate various summaries and to control their contents by providing the explicit targets for a reference to the model as controllable factors. In the experiments, we used five-minute or one-hour charts of 9 indicators (e.g., Nikkei225), as time-series data, and daily summaries of Nikkei Quick News as textual data. We conducted comparative experiments using two pieces of information: human-designed topic labels indicating the contents of a sentence and automatically extracted keywords as the referential information for generation.


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Generating Market Comments Referring to External Resources
Tatsuya Aoki | Akira Miyazawa | Tatsuya Ishigaki | Keiichi Goshima | Kasumi Aoki | Ichiro Kobayashi | Hiroya Takamura | Yusuke Miyao
Proceedings of the 11th International Conference on Natural Language Generation

Comments on a stock market often include the reason or cause of changes in stock prices, such as “Nikkei turns lower as yen’s rise hits exporters.” Generating such informative sentences requires capturing the relationship between different resources, including a target stock price. In this paper, we propose a model for automatically generating such informative market comments that refer to external resources. We evaluated our model through an automatic metric in terms of BLEU and human evaluation done by an expert in finance. The results show that our model outperforms the existing model both in BLEU scores and human judgment.


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Distinguishing Japanese Non-standard Usages from Standard Ones
Tatsuya Aoki | Ryohei Sasano | Hiroya Takamura | Manabu Okumura
Proceedings of the 2017 Conference on Empirical Methods in Natural Language Processing

We focus on non-standard usages of common words on social media. In the context of social media, words sometimes have other usages that are totally different from their original. In this study, we attempt to distinguish non-standard usages on social media from standard ones in an unsupervised manner. Our basic idea is that non-standardness can be measured by the inconsistency between the expected meaning of the target word and the given context. For this purpose, we use context embeddings derived from word embeddings. Our experimental results show that the model leveraging the context embedding outperforms other methods and provide us with findings, for example, on how to construct context embeddings and which corpus to use.