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  <front>
    <journal-meta>
      <journal-title-group>
        <journal-title>Prague, Czech Republic, July</journal-title>
      </journal-title-group>
    </journal-meta>
    <article-meta>
      <title-group>
        <article-title>Three Facets of Online Political Networks: Communities, Antagonisms and Controversial Issues</article-title>
      </title-group>
      <contrib-group>
        <contrib contrib-type="author">
          <string-name>Online Political Networks</string-name>
          <xref ref-type="aff" rid="aff0">0</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Community Detection</string-name>
          <xref ref-type="aff" rid="aff0">0</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Negative Link Prediction</string-name>
          <xref ref-type="aff" rid="aff0">0</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Sentiment Analysis</string-name>
          <xref ref-type="aff" rid="aff0">0</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Word Embedding</string-name>
          <xref ref-type="aff" rid="aff0">0</xref>
        </contrib>
        <aff id="aff0">
          <label>0</label>
          <institution>Mert Ozer School of Computing</institution>
          ,
          <addr-line>Informatics</addr-line>
          ,
          <institution>and Decision Systems Engineering Arizona State University Tempe</institution>
          ,
          <country country="US">US</country>
        </aff>
      </contrib-group>
      <pub-date>
        <year>2017</year>
      </pub-date>
      <volume>04</volume>
      <issue>2017</issue>
      <fpage>04</fpage>
      <lpage>07</lpage>
      <abstract>
        <p>Without any doubt, for the last decade, online social networks have been hubs for political participation both for elite members such as politicians, parliamentary members, and ordinary citizens. Each online activity leaves digital traces of the users participating which enable researchers to study online political behavior and build multi-faceted sensors to understand the underlying dynamics. In this talk, I broadly focus on three facets of online political behaviors of users and how to model them. First, I investigate the formations of communities in online political networks. Second, I focus on detecting negative linkages between users such as enmities or antagonisms. ird, I present the problem of the controversial issue and frame detection in online political networks. For each part, I give one exemplary recent work and possible future directions to take.</p>
      </abstract>
    </article-meta>
  </front>
  <body>
    <sec id="sec-1">
      <title>BACKGROUND AND SUMMARY</title>
      <p>
        Online social networks have been aracting people from a wide
range of political spectrum for the last decade to express their
political opinions, share the news that they care with their contacts, form
groups and debate with or against each other. Beyond individual
participation, protests are organized [
        <xref ref-type="bibr" rid="ref7">7</xref>
        ], [
        <xref ref-type="bibr" rid="ref12">12</xref>
        ], new alt-right
movements emerge [
        <xref ref-type="bibr" rid="ref3">3</xref>
        ], terrorist organizations recruit [
        <xref ref-type="bibr" rid="ref11">11</xref>
        ] and many
other political activities reside in online environments. Most
importantly they leave an immense amount of digital footprints while
participating. ese traces of people’s online political activities
give researchers unequivocal opportunities to analyze, reason and
predict the human behavior in online political seings.
      </p>
      <p>e challenges of conventional social media mining research
is present for political sub-domain of social media data as well.
Sparsity of the user network and short and noisy nature of textual
content constitute the major body of the challenges. Moreover, in
the political sub-domain a high level of irony and indirectness are
involved. In this talk, I focus on three dimensions of multi-faceted
human activity in online political networks,
online communities and what do users have in common in
a politically pure online community,
antagonisms, enmities or any other form of negative
linkages between users in online political networks,
and controversial issues causing polarization in online
political networks and frames each side puts forward for
issues.</p>
      <p>Further details for each dimension are given in Section 1.1, 1.2,
and 1.3, respectively. I give one recent proposed model for each
dimension of online political activities of users and possible future
directions for research.
1.1</p>
    </sec>
    <sec id="sec-2">
      <title>Community Detection</title>
      <p>
        Community detection is an integral part of studying online political
networks. A community in an online political network is a group of
users which interact with each other more than they interact with
others and share similar characteristics in terms of their political
belongings. Many studies show that endorsement network of users
gives invaluable piece of information to detect underlying politically
pure communities. For example, in the political sub-domain of
Twier, retweet network of politically motivated users uncover
the political identities of groups [
        <xref ref-type="bibr" rid="ref1">1</xref>
        ], broadly. However, the sparse
nature of endorsement networks challenges to identify political
groups in complete chunks. Many users do not endorse each other
although they propagate similar political contents. It may be simply
because they do not know each other.
      </p>
      <p>
        In this talk, a recent work [
        <xref ref-type="bibr" rid="ref8">8</xref>
        ] that tackles the sparsity problem
by employing network-independent features of users is presented.
e role textual content, shared article URLs and platform specic
content tags (i.e. hashtags) play in formation of communities is
studied by proposing three dierent non-negative matrix
factorization frameworks. e work also incorporates social balance
theory to introduce new articial endorsement links between users
to overcome the sparsity problem. Possible future directions are
investigated in three folds; temporal dynamics of communities,
emerging and fading communities.
of it. e more distant the vectors of the issue are the more dierent
frames are used for the issue by each communities.
      </p>
    </sec>
    <sec id="sec-3">
      <title>1.2 Negative Link Prediction</title>
      <p>Capturing disagreements, antagonisms, and enmities constitutes
another vital dimension of understanding online political activities
of users. ey may be even more informative than detecting
alliances, agreements or coalitions in the seings where endorsement
and sharing is motivated by the online platform. Two typical
examples are Facebook and Twier in which features of endorsement
and sharing is available in dierent forms such as retweet, like or
share while opposition, disagreement or any form of denouncement
are not. Features of platform-specic positive interactions help us
to understand the nature of positive links between users. However,
capturing negative links is a much more challenging task since
there is no explicit “dislike” feature in major online social network
platforms.</p>
      <p>
        In the talk, a recent work [
        <xref ref-type="bibr" rid="ref10">10</xref>
        ] which suggests exploring
sentiment signals in textual interactions, platform-specic positive
interactions and their composition for negative link prediction is briey
discussed. e work assumes that if textual interactions of two
users (i.e. mentioning in Twier) carry many negative sentiment
words, two users likely to form negative link between each other.
It further assumes two users to have a positive link in between if
they use any platform-specic positive interactions towards each
other. It also follows simple social balance rules such that enemy
of my enemy is my friend and friend of my friend is my friend to
advance the link prediction model. In the talk, two applications
of the framework are presented to show the added value of the
negative links in detecting communities more accurately and in
describing rivalries and coalitions more eectively.
1.3 Issue and Frame Detection
e last facet of understanding online political activities of users
this talk focuses is detecting controversial issues and frames.
Online social network users express their opinions on various political
issues. Needless to say, each user brings its own perspective and
nuances are inevitable. Characterizing which issues polarize online
crowds, while which issues bring communities closer is a key to
understand the dynamics behind formation of coalitions and conicts.
Moreover, capturing the sides communities take for a
controversial issue correctly is also valuable. Although it is a well studied
problem for conventional text documents such as parliamentary
oor debate records, a few eort has been put forward for detecting
controversial issues for online social networks [
        <xref ref-type="bibr" rid="ref4">4</xref>
        ] [
        <xref ref-type="bibr" rid="ref5">5</xref>
        ] [
        <xref ref-type="bibr" rid="ref6">6</xref>
        ].
      </p>
      <p>
        By [
        <xref ref-type="bibr" rid="ref2">2</xref>
        ], framing is dened as selecting some aspects of a perceived
reality and make them more salient in a communicating text. A
recent work [
        <xref ref-type="bibr" rid="ref9">9</xref>
        ] that incorporates the concept of framing to capture
controversial issues into a word embedding model is discussed to
illustrate a solution to the problem of issue and frame detection. It
proposes to model dimensions of embedding space as frames that
are highlighted by dierent groups. en, it computes a unique
community specic vector representation of each issue. e
distance between community specic word vector representations of
each issue becomes an eective metric to quantify the controversy
      </p>
    </sec>
  </body>
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