We mainly investigate word influence in neural sentiment classification, which results in a novel approach to promoting word sentiment and negation as attentions. Particularly, a sentiment and negation neural network (SNNN) is proposed, including a sentiment neural network (SNN) and a negation neural network (NNN). First, we modify the word level by embedding the word sentiment and negation information as the extra layers for the input. Second, we adopt a hierarchical LSTM model to generate the word-level, sentence-level and document-level representations respectively. After that, we enhance word sentiment and negation as attentions over the semantic level. Finally, the experiments conducting on the IMDB and Yelp data sets show that our approach is superior to the state-of-the-art baselines. Furthermore, we draw the interesting conclusions that (1) LSTM performs better than CNN and RNN for neural sentiment classification; (2) word sentiment and negation are a strong alliance with attention, while overfitting occurs when they are simultaneously applied at the embedding layer; and (3) word sentiment/negation can be singly implemented for better performance as both embedding layer and attention at the same time.
Gao, Dehong (The Hong Kong Polytechnic University) | Wei, Furu (Microsoft Research Asia, Beijing) | Li, Wenjie (The Hong Kong Polytechnic University) | Liu, Xiaohua (Microsoft Research Asia, Beijing) | Zhou, Ming (Microsoft Research Asia, Beijing)
In this paper, we address the issue of bilingual sentiment lexicon learning(BSLL) which aims to automatically and simultaneously generate sentiment words for two languages. The underlying motivation is that sentiment information from two languages can perform iterative mutual-teaching in the learning procedure. We propose to develop two classifiers to determine the sentiment polarities of words under a co-training framework, which makes full use of the two-view sentiment information from the two languages. The word alignment derived from the parallel corpus is leveraged to design effective features and to bridge the learning of the two classifiers. The experimental results on English and Chinese languages show the effectiveness of our approach in BSLL.
We describe a state-of-the-art sentiment analysis system that detects (a) the sentiment of short informal textual messages such as tweets and SMS (message-level task) and (b) the sentiment of a word or a phrase within a message (term-level task). The system is based on a supervised statistical text classification approach leveraging a variety of surface-form, semantic, and sentiment features. The sentiment features are primarily derived from novel high-coverage tweet-specific sentiment lexicons. These lexicons are automatically generated from tweets with sentiment-word hashtags and from tweets with emoticons. To adequately capture the sentiment of words in negated contexts, a separate sentiment lexicon is generated for negated words. The system ranked first in the SemEval-2013 shared task `Sentiment Analysis in Twitter' (Task 2), obtaining an F-score of 69.02 in the message-level task and 88.93 in the term-level task. Post-competition improvements boost the performance to an F-score of 70.45 (message-level task) and 89.50 (term-level task). The system also obtains state-of-the-art performance on two additional datasets: the SemEval-2013 SMS test set and a corpus of movie review excerpts. The ablation experiments demonstrate that the use of the automatically generated lexicons results in performance gains of up to 6.5 absolute percentage points.
The word soft may evoke positive connotations of warmth and cuddliness in many contexts, but calling a hockey player soft would be an insult. If you were to say something was terrific in the 1800s, this would probably imply that it was terrifying and awe-inspiring; today, terrific basically just implies that something is (pretty) good.
With the development of Web 2.0, sentiment analysis has now become a popular research problem to tackle. Recently, topic models have been introduced for the simultaneous analysis for topics and the sentiment in a document. These studies, which jointly model topic and sentiment, take the advantage of the relationship between topics and sentiment, and are shown to be superior to traditional sentiment analysis tools. However, most of them make the assumption that, given the parameters, the sentiments of the words in the document are all independent. In our observation, in contrast, sentiments are expressed in a coherent way. The local conjunctive words, such as “and” or “but”, are often indicative of sentiment transitions. In this paper, we propose a major departure from the previous approaches by making two linked contributions. First, we assume that the sentiments are related to the topic in the document, and put forward a joint sentiment and topic model, i.e. Sentiment-LDA. Second, we observe that sentiments are dependent on local context. Thus, we further extend the Sentiment-LDA model to Dependency-Sentiment-LDA model by relaxing the sentiment independent assumption in Sentiment-LDA. The sentiments of words are viewed as a Markov chain in Dependency-Sentiment-LDA. Through experiments, we show that exploiting the sentiment dependency is clearly advantageous, and that the Dependency-Sentiment-LDA is an effective approach for sentiment analysis.