333 research outputs found
Automatic Wrapper Adaptation by Tree Edit Distance Matching
Information distributed through the Web keeps growing faster day by day,\ud
and for this reason, several techniques for extracting Web data have been suggested\ud
during last years. Often, extraction tasks are performed through so called wrappers,\ud
procedures extracting information from Web pages, e.g. implementing logic-based\ud
techniques. Many fields of application today require a strong degree of robustness\ud
of wrappers, in order not to compromise assets of information or reliability of data\ud
extracted.\ud
Unfortunately, wrappers may fail in the task of extracting data from a Web page, if\ud
its structure changes, sometimes even slightly, thus requiring the exploiting of new\ud
techniques to be automatically held so as to adapt the wrapper to the new structure\ud
of the page, in case of failure. In this work we present a novel approach of automatic wrapper adaptation based on the measurement of similarity of trees through\ud
improved tree edit distance matching techniques
Quantifying the Effect of Sentiment on Information Diffusion in Social Media
Social media have become the main vehicle of information production and
consumption online. Millions of users every day log on their Facebook or
Twitter accounts to get updates and news, read about their topics of interest,
and become exposed to new opportunities and interactions. Although recent
studies suggest that the contents users produce will affect the emotions of
their readers, we still lack a rigorous understanding of the role and effects
of contents sentiment on the dynamics of information diffusion. This work aims
at quantifying the effect of sentiment on information diffusion, to understand:
(i) whether positive conversations spread faster and/or broader than negative
ones (or vice-versa); (ii) what kind of emotions are more typical of popular
conversations on social media; and, (iii) what type of sentiment is expressed
in conversations characterized by different temporal dynamics. Our findings
show that, at the level of contents, negative messages spread faster than
positive ones, but positive ones reach larger audiences, suggesting that people
are more inclined to share and favorite positive contents, the so-called
positive bias. As for the entire conversations, we highlight how different
temporal dynamics exhibit different sentiment patterns: for example, positive
sentiment builds up for highly-anticipated events, while unexpected events are
mainly characterized by negative sentiment. Our contribution is a milestone to
understand how the emotions expressed in short texts affect their spreading in
online social ecosystems, and may help to craft effective policies and
strategies for content generation and diffusion.Comment: 10 pages, 5 figure
Design of Automatically Adaptable Web Wrappers
Nowadays, the huge amount of information distributed through the Web motivates studying techniques to\ud
be adopted in order to extract relevant data in an efficient and reliable way. Both academia and enterprises\ud
developed several approaches of Web data extraction, for example using techniques of artificial intelligence or\ud
machine learning. Some commonly adopted procedures, namely wrappers, ensure a high degree of precision\ud
of information extracted from Web pages, and, at the same time, have to prove robustness in order not to\ud
compromise quality and reliability of data themselves.\ud
In this paper we focus on some experimental aspects related to the robustness of the data extraction process\ud
and the possibility of automatically adapting wrappers. We discuss the implementation of algorithms for\ud
finding similarities between two different version of a Web page, in order to handle modifications, avoiding\ud
the failure of data extraction tasks and ensuring reliability of information extracted. Our purpose is to evaluate\ud
performances, advantages and draw-backs of our novel system of automatic wrapper adaptation
Measuring Emotional Contagion in Social Media
Social media are used as main discussion channels by millions of individuals
every day. The content individuals produce in daily social-media-based
micro-communications, and the emotions therein expressed, may impact the
emotional states of others. A recent experiment performed on Facebook
hypothesized that emotions spread online, even in absence of non-verbal cues
typical of in-person interactions, and that individuals are more likely to
adopt positive or negative emotions if these are over-expressed in their social
network. Experiments of this type, however, raise ethical concerns, as they
require massive-scale content manipulation with unknown consequences for the
individuals therein involved. Here, we study the dynamics of emotional
contagion using Twitter. Rather than manipulating content, we devise a null
model that discounts some confounding factors (including the effect of
emotional contagion). We measure the emotional valence of content the users are
exposed to before posting their own tweets. We determine that on average a
negative post follows an over-exposure to 4.34% more negative content than
baseline, while positive posts occur after an average over-exposure to 4.50%
more positive contents. We highlight the presence of a linear relationship
between the average emotional valence of the stimuli users are exposed to, and
that of the responses they produce. We also identify two different classes of
individuals: highly and scarcely susceptible to emotional contagion. Highly
susceptible users are significantly less inclined to adopt negative emotions
than the scarcely susceptible ones, but equally likely to adopt positive
emotions. In general, the likelihood of adopting positive emotions is much
greater than that of negative emotions.Comment: 10 pages, 5 figure
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