<?xml version="1.0" encoding="ISO-8859-1"?><article xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
<front>
<journal-meta>
<journal-id>1405-5546</journal-id>
<journal-title><![CDATA[Computación y Sistemas]]></journal-title>
<abbrev-journal-title><![CDATA[Comp. y Sist.]]></abbrev-journal-title>
<issn>1405-5546</issn>
<publisher>
<publisher-name><![CDATA[Instituto Politécnico Nacional, Centro de Investigación en Computación]]></publisher-name>
</publisher>
</journal-meta>
<article-meta>
<article-id>S1405-55462021000300647</article-id>
<article-id pub-id-type="doi">10.13053/cys-25-3-3907</article-id>
<title-group>
<article-title xml:lang="en"><![CDATA[Wardp HMM: A Shilling Attack Detection Technique Using Wardp Method and Hidden Markov Model]]></article-title>
</title-group>
<contrib-group>
<contrib contrib-type="author">
<name>
<surname><![CDATA[Chowdhury]]></surname>
<given-names><![CDATA[Keya]]></given-names>
</name>
<xref ref-type="aff" rid="Aff"/>
</contrib>
<contrib contrib-type="author">
<name>
<surname><![CDATA[Majumder]]></surname>
<given-names><![CDATA[Abhishek]]></given-names>
</name>
<xref ref-type="aff" rid="Aff"/>
</contrib>
<contrib contrib-type="author">
<name>
<surname><![CDATA[Sarkar]]></surname>
<given-names><![CDATA[Joy Lal]]></given-names>
</name>
<xref ref-type="aff" rid="Aff"/>
</contrib>
<contrib contrib-type="author">
<name>
<surname><![CDATA[Chakraborty]]></surname>
<given-names><![CDATA[Sukanta]]></given-names>
</name>
<xref ref-type="aff" rid="Aff"/>
</contrib>
<contrib contrib-type="author">
<name>
<surname><![CDATA[Roy]]></surname>
<given-names><![CDATA[Sudipta]]></given-names>
</name>
<xref ref-type="aff" rid="Aff"/>
</contrib>
</contrib-group>
<aff id="Af1">
<institution><![CDATA[,Tripura University Department of Computer Science &amp; Engineering ]]></institution>
<addr-line><![CDATA[ ]]></addr-line>
<country>India</country>
</aff>
<aff id="Af2">
<institution><![CDATA[,Assam University Department of Computer Science and Engineering ]]></institution>
<addr-line><![CDATA[ ]]></addr-line>
<country>India</country>
</aff>
<pub-date pub-type="pub">
<day>00</day>
<month>09</month>
<year>2021</year>
</pub-date>
<pub-date pub-type="epub">
<day>00</day>
<month>09</month>
<year>2021</year>
</pub-date>
<volume>25</volume>
<numero>3</numero>
<fpage>647</fpage>
<lpage>657</lpage>
<copyright-statement/>
<copyright-year/>
<self-uri xlink:href="http://www.scielo.org.mx/scielo.php?script=sci_arttext&amp;pid=S1405-55462021000300647&amp;lng=en&amp;nrm=iso"></self-uri><self-uri xlink:href="http://www.scielo.org.mx/scielo.php?script=sci_abstract&amp;pid=S1405-55462021000300647&amp;lng=en&amp;nrm=iso"></self-uri><self-uri xlink:href="http://www.scielo.org.mx/scielo.php?script=sci_pdf&amp;pid=S1405-55462021000300647&amp;lng=en&amp;nrm=iso"></self-uri><abstract abstract-type="short" xml:lang="en"><p><![CDATA[Abstract: Collaborative Filtering Recommender Systems (CFRSs) are widely employed in several applications because of its satisfying performance in the customized recommendation. Recent studies show that CFRSs are at risk of shilling attacks where attackers inject shilling profiles into the system. Malicious user injected ratings not only severely impact genuineness of recommendations but also user's trustworthiness within recommendation systems. Existing unsupervised clustering technique uses Ward method, which is an iterative method of low scalability. For addressing this issue, in this work an unsupervised SA detection technique named WardpHMM has been proposed. It uses Wardp and Hidden Markov Model (HMM). In this proposed method HMM is used to measure difference of user&#8217;s rating behavior. It generates User Suspicious Degree (USD) of each user by analyzing user&#8217;s Suspicious Degree Range of Items (SDRI) and User&#8217;s Matching Degree (UMD). Then Wardp method is applied to merge users based on USD and to acquire group of Attack Users (AUs). For performance analysis of the proposed technique, Amazon-ratings sample dataset was used. The performance comparison shows that proposed WardpHMM technique outperforms baseline technique with respect to precision, recall and F1-score.]]></p></abstract>
<kwd-group>
<kwd lng="en"><![CDATA[Profile injection attack]]></kwd>
<kwd lng="en"><![CDATA[Hidden Markov model]]></kwd>
<kwd lng="en"><![CDATA[user matching degree]]></kwd>
<kwd lng="en"><![CDATA[user suspicious degree]]></kwd>
<kwd lng="en"><![CDATA[Wardp method]]></kwd>
</kwd-group>
</article-meta>
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