Time: Tuesday 17th November 2009, 14:00
Place: Aalborg University, Selma Lagerløfs vej 300, room 02.13
Rank-aware query processing has attracted much interest lately, as users are often overwhelmed by the size of query results. Therefore, ranked queries help users to identify a limited set of the most interesting or representative results, thereby enabling effective decision-making. In this talk, we will focus on two types of queries, namely skyline queries and reverse top-k queries.
Skyline queries have been proposed for discovering a set of interesting points. Unfortunately, as the dimensionality of the dataset grows, the skyline operator loses its discriminating power and returns a large fraction of the data. In this talk, I will present several interesting properties of the skyline points that lead to discovering the most important skyline points, and therefore to a ranking method of skyline points. On the other hand, top-k queries retrieve only the k objects that best match the user preferences, thus avoiding huge and overwhelming result sets. Top-k queries have been mainly studied from the perspective of the user. In this talk, I will present a novel query type, namely reverse top-k queries, that handles top-k queries from the perspective of the product manufacturer, by providing answers to questions like: “Given a potential product, which are the user preferences for which this product is in the top-k query result set”?
Akrivi Vlachou is currently a researcher in the database group of Prof.Kjetil Noervaag at the Norwegian University of Science and Technology. She has been awarded an ERCIM “Alain Bensoussan” fellowship for post-doctoral studies in 2009. She received her PhD in 2008 entitled “Efficient Query Processing over Highly Distributed Data” from the Athens University of Economics and Business supervised by Prof.Michalis Vazirgiannis. She received her Master of science in “Advanced Information Systems” and her Diploma in “Computer Science and Telecommunications” from the Department of Computer Science, University of Athens in 2001 and 2003 respectively. Her research interests lie in query processing and data management in large-scale distributed systems.