Hitoshi Nishikawa


2018

pdf bib
Analysis of Implicit Conditions in Database Search Dialogues
Shun-ya Fukunaga | Hitoshi Nishikawa | Takenobu Tokunaga | Hikaru Yokono | Tetsuro Takahashi
Proceedings of the Eleventh International Conference on Language Resources and Evaluation (LREC 2018)

pdf bib
Interpretation of Implicit Conditions in Database Search Dialogues
Shunya Fukunaga | Hitoshi Nishikawa | Takenobu Tokunaga | Hikaru Yokono | Tetsuro Takahashi
Proceedings of the 27th International Conference on Computational Linguistics

Targeting the database search dialogue, we propose to utilise information in the user utterances that do not directly mention the database (DB) field of the backend database system but are useful for constructing database queries. We call this kind of information implicit conditions. Interpreting the implicit conditions enables the dialogue system more natural and efficient in communicating with humans. We formalised the interpretation of the implicit conditions as classifying user utterances into the related DB field while identifying the evidence for that classification at the same time. Introducing this new task is one of the contributions of this paper. We implemented two models for this task: an SVM-based model and an RCNN-based model. Through the evaluation using a corpus of simulated dialogues between a real estate agent and a customer, we found that the SVM-based model showed better performance than the RCNN-based model.

pdf bib
Effectiveness of Domain Adaptation in Japanese Predicate-Argument Structure Analysis
Mizuki Sango | Hitoshi Nishikawa | Takenobu Tokunaga
Proceedings of the 32nd Pacific Asia Conference on Language, Information and Computation

pdf bib
Neural Japanese Zero Anaphora Resolution using Smoothed Large-scale Case Frames with Word Embedding
Souta Yamashiro | Hitoshi Nishikawa | Takenobu Tokunaga
Proceedings of the 32nd Pacific Asia Conference on Language, Information and Computation

2017

pdf bib
An Eye-tracking Study of Named Entity Annotation
Takenobu Tokunaga | Hitoshi Nishikawa | Tomoya Iwakura
Proceedings of the International Conference Recent Advances in Natural Language Processing, RANLP 2017

Utilising effective features in machine learning-based natural language processing (NLP) is crucial in achieving good performance for a given NLP task. The paper describes a pilot study on the analysis of eye-tracking data during named entity (NE) annotation, aiming at obtaining insights into effective features for the NE recognition task. The eye gaze data were collected from 10 annotators and analysed regarding working time and fixation distribution. The results of the preliminary qualitative analysis showed that human annotators tend to look at broader contexts around the target NE than recent state-of-the-art automatic NE recognition systems and to use predicate argument relations to identify the NE categories.

2016

pdf bib
An extension of ISO-Space for annotating object direction
Daiki Gotou | Hitoshi Nishikawa | Takenobu Tokunaga
Proceedings of the 12th Workshop on Asian Language Resources (ALR12)

In this paper, we extend an existing annotation scheme ISO-Space for annotating necessary spatial information for the task placing an specified object at a specified location with a specified direction according to a natural language instruction. We call such task the spatial placement problem. Our extension particularly focuses on describing the object direction, when the object is placed on the 2D plane. We conducted an annotation experiment in which a corpus of 20 situated dialogues were annotated. The annotation result showed the number of newly introduced tags by our proposal is not negligible. We also implemented an analyser that automatically assigns the proposed tags to the corpus and evaluated its performance. The result showed that the performance for entity tag was quite high ranging from 0.68 to 0.99 in F-measure, but not the case for relation tags, i.e. less than 0.4 in F-measure.

pdf bib
Parameter estimation of Japanese predicate argument structure analysis model using eye gaze information
Ryosuke Maki | Hitoshi Nishikawa | Takenobu Tokunaga
Proceedings of COLING 2016, the 26th International Conference on Computational Linguistics: Technical Papers

In this paper, we propose utilising eye gaze information for estimating parameters of a Japanese predicate argument structure (PAS) analysis model. We employ not only linguistic information in the text, but also the information of annotator eye gaze during their annotation process. We hypothesise that annotator’s frequent looks at certain candidates imply their plausibility of being the argument of the predicate. Based on this hypothesis, we consider annotator eye gaze for estimating the model parameters of the PAS analysis. The evaluation experiment showed that introducing eye gaze information increased the accuracy of the PAS analysis by 0.05 compared with the conventional methods.

2014

pdf bib
Learning to Generate Coherent Summary with Discriminative Hidden Semi-Markov Model
Hitoshi Nishikawa | Kazuho Arita | Katsumi Tanaka | Tsutomu Hirao | Toshiro Makino | Yoshihiro Matsuo
Proceedings of COLING 2014, the 25th International Conference on Computational Linguistics: Technical Papers

2013

pdf bib
A Pilot Study of Readability Prediction with Reading Time
Hitoshi Nishikawa | Toshiro Makino | Yoshihiro Matsuo
Proceedings of the Second Workshop on Predicting and Improving Text Readability for Target Reader Populations

2012

pdf bib
Text Summarization Model based on Redundancy-Constrained Knapsack Problem
Hitoshi Nishikawa | Tsutomu Hirao | Toshiro Makino | Yoshihiro Matsuo
Proceedings of COLING 2012: Posters

pdf bib
Grammar Error Correction Using Pseudo-Error Sentences and Domain Adaptation
Kenji Imamura | Kuniko Saito | Kugatsu Sadamitsu | Hitoshi Nishikawa
Proceedings of the 50th Annual Meeting of the Association for Computational Linguistics (Volume 2: Short Papers)

2010

pdf bib
Learning to Model Domain-Specific Utterance Sequences for Extractive Summarization of Contact Center Dialogues
Ryuichiro Higashinaka | Yasuhiro Minami | Hitoshi Nishikawa | Kohji Dohsaka | Toyomi Meguro | Satoshi Takahashi | Genichiro Kikui
Coling 2010: Posters

pdf bib
Opinion Summarization with Integer Linear Programming Formulation for Sentence Extraction and Ordering
Hitoshi Nishikawa | Takaaki Hasegawa | Yoshihiro Matsuo | Genichiro Kikui
Coling 2010: Posters

pdf bib
Optimizing Informativeness and Readability for Sentiment Summarization
Hitoshi Nishikawa | Takaaki Hasegawa | Yoshihiro Matsuo | Genichiro Kikui
Proceedings of the ACL 2010 Conference Short Papers