Abstract

This paper presents a supervised Aspect Based Sentiment Analysis (ABSA) system. Our aim is to develop a modular platform which allows to easily conduct experiments by replacing the modules or adding new features. We obtain the best result in the Opinion Target Extraction (OTE) task (slot 2) using an off-the-shelf sequence labeler. The target polarity classification (slot 3) is addressed by means of a multiclass SVM algorithm which includes lexical based features such as the polarity values obtained from domain and open polarity lexicons. The system obtains accuracies of 0.70 and 0.73 for the restaurant and laptop domain respectively, and performs second best in the out-of-domain hotel, achieving an accuracy of 0.80.

Highlights

  • Nowadays Sentiment Analysis is proving very useful for tasks such as decision making and market analysis

  • Research has been evolving towards specific opinion elements such as entities or properties of a certain opinion target, which is known as Aspect Based Sentiment Analysis (ABSA)

  • The results show that leveraging unlabeled text is helpful in the Opinion Target Extraction (OTE) task, obtaining an increase of 7 points in recall

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Summary

Introduction

Nowadays Sentiment Analysis is proving very useful for tasks such as decision making and market analysis. The Semeval 2015 ABSA shared task aims at covering the. 1http://challenges.2014.eswcconferences.org/index.php/SemSA most common problems in an ABSA task: detecting the specific topics an opinion refers to (slot1); extracting the opinion targets (slot2), combining the topic and target identification (slot1&2) and, computing the polarity of the identified word/targets (slot). Participants were allowed to send one constrained (no external resources allowed) and one unconstrained run for each subtask. Our main is to develop an ABSA system to be used in the future for further experimentation. Rather than focusing on tuning the different modules our main goal is to develop a platform to facilitate future experimentation. Section describes the external resources used in the unconstrained systems.

Corpora
Polarity Lexicons
Slot2 Subtask
Slot3 Subtask
Baseline
Window
Feature combinations
Results
Conclusions
Full Text
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