17 research outputs found
Better Document-level Sentiment Analysis from RST Discourse Parsing
Discourse structure is the hidden link between surface features and
document-level properties, such as sentiment polarity. We show that the
discourse analyses produced by Rhetorical Structure Theory (RST) parsers can
improve document-level sentiment analysis, via composition of local information
up the discourse tree. First, we show that reweighting discourse units
according to their position in a dependency representation of the rhetorical
structure can yield substantial improvements on lexicon-based sentiment
analysis. Next, we present a recursive neural network over the RST structure,
which offers significant improvements over classification-based methods.Comment: Published at Empirical Methods in Natural Language Processing (EMNLP
2015
Neural Discourse Structure for Text Categorization
We show that discourse structure, as defined by Rhetorical Structure Theory
and provided by an existing discourse parser, benefits text categorization. Our
approach uses a recursive neural network and a newly proposed attention
mechanism to compute a representation of the text that focuses on salient
content, from the perspective of both RST and the task. Experiments consider
variants of the approach and illustrate its strengths and weaknesses.Comment: ACL 2017 camera ready versio
Measuring, Characterizing, and Detecting Facebook Like Farms
Social networks offer convenient ways to seamlessly reach out to large
audiences. In particular, Facebook pages are increasingly used by businesses,
brands, and organizations to connect with multitudes of users worldwide. As the
number of likes of a page has become a de-facto measure of its popularity and
profitability, an underground market of services artificially inflating page
likes, aka like farms, has emerged alongside Facebook's official targeted
advertising platform. Nonetheless, there is little work that systematically
analyzes Facebook pages' promotion methods. Aiming to fill this gap, we present
a honeypot-based comparative measurement study of page likes garnered via
Facebook advertising and from popular like farms. First, we analyze likes based
on demographic, temporal, and social characteristics, and find that some farms
seem to be operated by bots and do not really try to hide the nature of their
operations, while others follow a stealthier approach, mimicking regular users'
behavior. Next, we look at fraud detection algorithms currently deployed by
Facebook and show that they do not work well to detect stealthy farms which
spread likes over longer timespans and like popular pages to mimic regular
users. To overcome their limitations, we investigate the feasibility of
timeline-based detection of like farm accounts, focusing on characterizing
content generated by Facebook accounts on their timelines as an indicator of
genuine versus fake social activity. We analyze a range of features, grouped
into two main categories: lexical and non-lexical. We find that like farm
accounts tend to re-share content, use fewer words and poorer vocabulary, and
more often generate duplicate comments and likes compared to normal users.
Using relevant lexical and non-lexical features, we build a classifier to
detect like farms accounts that achieves precision higher than 99% and 93%
recall.Comment: To appear in ACM Transactions on Privacy and Security (TOPS
A Hybrid Approach to the Sentiment Analysis Problem at the Sentence Level
The file attached to this record is the author's final peer reviewed version. The Publisher's final version can be found by following the DOI link.The objective of this article is to present a hybrid approach to the Sentiment Analysis problem at the sentence level. This new method uses natural language processing (NLP) essential techniques, a sentiment lexicon enhanced with the assistance of SentiWordNet, and fuzzy sets to estimate the semantic orientation polarity and its intensity for sentences, which provides a foundation for computing with sentiments. The proposed hybrid method is applied to three different data-sets and the results achieved are compared to those obtained using Naïve Bayes and Maximum Entropy techniques. It is demonstrated that the presented hybrid approach is more accurate and precise than both Naïve Bayes and Maximum Entropy techniques, when the latter are utilised in isolation. In addition, it is shown that when applied to datasets containing snippets, the proposed method performs similarly to state of the art techniques
From Discourse Structure To Text Specificity: Studies Of Coherence Preferences
To successfully communicate through text, a writer needs to organize information into an understandable and well-structured discourse for the targeted audience. This involves deciding when to convey general statements, when to elaborate on details, and gauging how much details to convey, i.e., the level of specificity. This thesis explores the automatic prediction of text specificity, and whether the perception of specificity varies across different audiences.
We characterize text specificity from two aspects: the instantiation discourse relation, and the specificity of sentences and words. We identify characteristics of instantiation that signify a change of specificity between sentences. Features derived from these characteristics substantially improve the detection of the relation. Using instantiation sentences as the basis for training, we propose a semi-supervised system to predict sentence specificity with speed and accuracy. Furthermore, we present insights into the effect of underspecified words and phrases on the comprehension of text, and the prediction of such words.
We show distinct preferences in specificity and discourse structure among different audiences. We investigate these distinctions in both cross-lingual and monolingual context. Cross-lingually, we identify discourse factors that significantly impact the quality of text translated from Chinese to English. Notably, a large portion of Chinese sentences are significantly more specific and need to be translated into multiple English sentences. We introduce a system using rich syntactic features to accurately detect such sentences. We also show that simplified text is more general, and that specific sentences are more likely to need simplification. Finally, we present evidence that the perception of sentence specificity differs among male and female readers