Alexandros Ntoulas is a Researcher at Microsoft Research in Mountain View, California since 2006. He received his Ph.D. and M.Sc. degrees in Computer Science from the University of California Los Angeles (UCLA) in 2006 and 2003 respectively. He has also received an Engineering Diploma from the Computer Engineering and Informatics Department (CEID) of Patras University, Greece in 2000. He was the co-founder of Infocious, a Web Search Engine indexing more than 2.5 billion pages that applied semantic analysis techniques in order to provide highly relevant results and a better search experience to the user. The company relaunched as Lingo Spot in 2007.

His research falls in the area of Web Information Systems. In particular, he is interested in systems and algorithms that facilitate the monitoring, collection, management, mining and searching of information on the World Wide Web. He is currently working on task-centric Web search, i.e. on a project aiming at detecting, modeling and supporting the task-oriented nature of several search sessions on the Web. Such task-oriented searches typically span several days of search activity for researching, learning, comparing and deciding and may involve other people from the user's social network. He is also working on a search prototype that aims at identifying and exploiting structure in keyword queries and mixing Web results with results coming from structured data sources that are abundant in the Hidden Web.

He is the recipient of the Best Paper Award for the ICDE 2005 conference, and a runner-up for the Best Paper Award in WWW 2009.

• Ph.D. Computer Science Department, University of California Los Angeles (UCLA), 2006.
  Advisor: Professor Junghoo "John" Cho.
  Dissertation Title: Crawling and Searching the Hidden Web.
  
  
• M.Sc. Computer Science Department, University of California Los Angeles (UCLA), 2003.
  Advisor: Professor Junghoo "John" Cho.
  
  
• M.Sc. Computer Engineering and Informatics Department, Patras University, 2003.
  Advisor: Professor Dimitris Christodoulakis
  Thesis Title: Automatic Web Directory Construction.
  
  
• B.Sc. Computer Engineering and Informatics Department, University of Patras, 2000.
  Advisor: Professor Dimitris Christodoulakis
  Thesis Title: A System for Managing and Querying Corpora.
  

The Web has brought together a wide variety of digital information into publicly accessible media. However, because of the sheer quantity and varying quality of available information, the user often feels overwhelmed and disoriented during his pursuit of information. My research focuses on the monitoring, collection, sharing, mining and searching of information in order to help the users identify and extract the desired information quickly and effectively through simple and intuitive methods.

Here is a list of some of the projects that I have worked on:

• Hidden-Web Crawling: Search engines employ automated programs called crawlers to download pages from the Web. Typical crawlers today follow links from one Web page to another and download every page in their path. However, an ever-increasing amount of information on the Web is accessible only through search interfaces; such information is called the Hidden or Deep Web. For example, in PubMed (www.pubmed.org) users can access pages of high-quality papers on medical research only after issuing a set of keywords. Since there are no static links to the Hidden-Web pages, current search engines cannot index them, thus depriving users from accessing potentially valuable information. In my research, I studied how we can build an effective Hidden-Web crawler that can autonomously discover and download pages from the Hidden Web.
  [ JCDL 2005 | extended version | slides ]

• Indexing Optimizations: Search engines typically create and maintain large-scale indexes that are used to answer thousands of user queries per second. Given the vast amount of information available on the Web, such indexes can easily grow very large and become very costly to operate. In my research, I proposed and evaluated algorithms for reducing the size of an index, without sacrificing the quality of results that we return to the users.
  [ SIGIR 2007 | slides ]

• Web Spam Detection: One of the most important goals of Web search engines is to return highly relevant results to the users. However, given the potential monetary value of the traffic that search engines direct to Web sites, some Web site operators craft spam Web pages that are useless to human users and exist for the sole purpose of fooling the search engine rankings into returning such pages, in the hope of attracting traffic. At Microsoft Research, we studied the characteristics of Web spam and proposed fast and highly accurate algorithms for removing spam from the search engine results.
  [ WWW 2006 | slides ]

• Data Synchronization: Information on the Web is constantly updated. Therefore, once the search engine’s crawler has downloaded pages and stored them locally, the crawler has to refresh the pages periodically. In my research, I performed large-scale experimental studies on several million pages collected weekly from the Web over a period of one year. We induced models that capture the evolution of Web sites and Web-accessible textual databases. The models were then used to predict when we should refresh the Web pages. Additionally, since the enormous size of the Web limits most crawlers to downloading only a subset of the entire Web, I studied sampling-based algorithms for determining which subset of the Web the crawler should focus on.
  [ VLDB 2002 , slides | WWW 2004 , slides | ICDE 2005 , slides ]

• The Infocious Web Search Engine: As part of my research, I worked on the implementation of a full-fledged commercial Web search engine called Infocious, which blends my research in crawling, data synchronization and indexing along with a variety of natural language processing (NLP) techniques in order to improve the quality of results presented to the users. The search engine performes highly efficient crawling and indexing of Web data, operates in a distributed fashion over a cluster of commodity machines, provides failover capabilities that guarantee 24/7 availability of the service, and gracefully scales to the size of the Web, currently indexing more than 2 billion pages.
  [ WWW 2005 | slides ]

• Automatic Web Directory Construction: Web Directories provide an alternative (to search engines) way of locating relevant information on the Web. Typically, Web Directories rely on humans putting in significant time and effort into finding important pages on the Web and categorizing them in the Directory. I studied ways for automating the creation of a Web Directory by assigning every page from a given collection of pages to a given subject hierarchy. Our method is based on the identification of important sequences of terms within Web pages (called lexical chains), which are then used to assign the pages to categories in the hierarchy.
  [ APWeb 2006 ]

• Releasing Search Queries and Clicks Privately: Researchers working within the realm of a real Web search engine have the privilege of accessing real query logs containing the queries and clicks that the users performed over large periods of time. Although such data is of tremendous value for research in the WWW and Social Networks areas, they are kept strictly confidential from Search Engine companies due to privacy concerns. At Microsoft Research, we worked on algorithms that would allow us to release queries and clicks from a real query log to third parties (users or researchers) while rigorously preverving user privacy.
  [ WWW 2009 ]

• Editorial board, Data Mining with Ontologies: Implementations, Findings and Frameworks, 2007
• Co-chair, Special Session on Web Search and Mining (PCI 2007)
• Reviewer, NSF Proposal Review Panel, Information and Intelligent Systems Program (2009)
• Program Committee, World Wide Web Conference (WWW 2010)
• Program Committee, Web Search and Data Mining Conference (WSDM 2010)
• Program Committee, ACM Information Retrieval Conference (SIGIR 2010)
• Program Committee, Very Large Databases Conference (VLDB 2010)
• Program Committee, Knowledge Discovery and Data Mining Conference (KDD 2010)
• Program Committee, International Conference on Data Engineering (ICDE 2010)
• Program Committee, World Wide Web Conference (WWW 2009)
• Program Committee, Adversarial Information Retrieval on the Web (AIRWeb 2009)
• Program Committee, ACM Intl. Conference on Web Search and Data Mining (WSDM 2008)
• Program Committee, European Conference on Machine Learning and Principles and Practice of Knowledge Discovery in Databases (ECML/PKDD 2008)
• Program Committee, World Wide Web Conference (WWW 2008)
• Program Committee, Adversarial Information Retrieval on the Web (AIRWeb 2008)
• Program Committee, ACM Intl. Workshop on Web Information & Data Management (WIDM 2007)
• Program Committee, Workshop on Improving Web Retrieval for non-English queries (SIGIR 2007)
• Program Committee, World Wide Web Conference (WWW 2006)
• Program Committee, ACM Hypertext 2005 Workshop on Peer to Peer and Service Oriented Hypermedia (HT 2005)
• Program Committee, World Wide Web Conference (WWW 2005)
• Referee, Transactions on Information Systems (TOIS)
• Referee, Transactions on Internet Technology (TOIT)
• Referee, Transactions on Web (TWeb)
• Referee, IEEE Transactions on Knowledge and Data Engineering (TKDE)

• New Scientist magazine article, 03/07/2009 Noise could mask web searchers' IDs
• ACM Tech News edition, 03/13/2009 Noise could mask web searchers' IDs
• TechFlash article, 04/23/2009 Microsoft: How to study search data without risking privacy
• Microsoft Research article, 04/22/2009 Making the Web More User-Friendly
• Search Engine Watch article, 08/28/2006 Identifying Web Spam

• Mailing Address:
  
  Alexandros Ntoulas
  Microsoft Research
  SVC-6/1040
  1065 La Avenida
  Mountain View, CA 94043, USA
  
  
• Email: ntoulas@cs.ucla.edu
  
• Office Phone: +1 (650) 693 2187
  
• Office Fax: +1 (650) 693 3329