Papers by Georgia Koutrika
As a large fraction of available information resides in databases, the need for facilitating acce... more As a large fraction of available information resides in databases, the need for facilitating access for the large majority of users becomes increasingly more important. Précis queries are free-form queries that generate entire multirelation databases, which are logical subsets of existing ones. A logical subset contains not only items directly related to the given query selections but also items implicitly related to them in various ways with the purpose of providing to the user much greater insight into the original data. This paper is concerned with the definition and generation of logical database subsets based on précis queries under a generalized perspective that removes several restrictions of previous work and handles queries containing multiple terms combined using the operators AN D, OR, and NOT .
D-Lib Magazine
The term "Digital Libraries" corresponds to a very complex notion with several diverse aspects an... more The term "Digital Libraries" corresponds to a very complex notion with several diverse aspects and cannot be captured by a simple definition. A robust model of Digital Libraries encapsulating the richness of these perspectives is required. This need has led to the drafting of The Digital Library Manifesto, the aim of which is to set the foundations and identify the cornerstone concepts within the universe of Digital Libraries, facilitating the integration of research results and proposing better ways of developing appropriate systems. The Manifesto is a result of the collaborative work of members of the European Union co-funded DELOS Network of Excellence on Digital Libraries. 1 It exploits the collective understanding that has been acquired, over more than a decade, on Digital Libraries by European research groups active in the Digital Library field, both within DELOS and outside, as well as by other groups around the world. This article presents the core parts of the Manifesto that introduce the entities of discourse of the Digital Library universe.
IEEE Transactions on Knowledge and Data Engineering, 2014
Abstract In this paper, we argue that preference-aware query processing needs to be pushed closer... more Abstract In this paper, we argue that preference-aware query processing needs to be pushed closer to the DBMS. We introduce a preference-aware relational data model that extends database tuples with preferences and an extended algebra that captures the essence of processing queries with preferences. Based on a set of algebraic properties and a cost model that we propose, we provide several query optimization strategies for extended query plans. Further, we describe a query execution algorithm that blends preference ...
22nd International Conference on Data Engineering (ICDE'06), 2006
Wide spread use of database systems in modern society has brought the need to provide inexperienc... more Wide spread use of database systems in modern society has brought the need to provide inexperienced users with the ability to easily search a database with no specific knowledge of a query language. Several recent research efforts have focused on supporting keyword-based searches over relational databases. This paper presents an alternative proposal and introduces the idea of précis queries. These are free-form queries whose answer (a précis) is a synthesis of results, containing not only information directly related to the query selections but also information implicitly related to them in various ways. Our approach to précis queries includes two additional novelties: (a) queries do not generate individual relations but entire multi-relation databases; and (b) query results are personalized to user-specific and/or domain requirements. We develop a framework and system architecture for supporting such queries in the context of a relational database system and describe algorithms that implement the required functionality. Finally, we present a set of experimental results that evaluate the proposed algorithms and show the potential of this work.
Proceedings of the 2005 ACM SIGMOD international conference on Management of data - SIGMOD '05, 2005
... algorithms are potentially applicable: genetic algorithms [5], simulated annealing [10], tabu... more ... algorithms are potentially applicable: genetic algorithms [5], simulated annealing [10], tabu search [4], etc. ... Personalized Query Construction: After 'CQP State Space Search' has selected the optimal ... can be effectively combined into one sub-query, but investigating the details of ...
Proceedings. 20th International Conference on Data Engineering, 2004
As information becomes available in increasing amounts to a wide spectrum of users, the need for ... more As information becomes available in increasing amounts to a wide spectrum of users, the need for a shift towards a more user-centered information access paradigm arises. We develop a personal-ization framework for database systems based on user profiles and identify the ...
21st International Conference on Data Engineering (ICDE'05), 2005
Query Personalization is the process of dynamically enhancing a query with related user preferenc... more Query Personalization is the process of dynamically enhancing a query with related user preferences stored in a user profile with the aim of providing personalized answers. The underlying idea is that different users may find different things relevant to a search due to different preferences. Essential ingredients of query personalization are: (a) a model for representing and storing preferences in user profiles, and (b) algorithms for the generation of personalized answers using stored preferences. Modeling the plethora of preference types is a challenge. In this paper, we present a preference model that combines expressivity and concision. In addition, we provide efficient algorithms for the selection of preferences related to a query, and an algorithm for the progressive generation of personalized results, which are ranked based on user interest. Several classes of ranking functions are provided for this purpose. We present results of experiments both synthetic and with real users (a) demonstrating the efficiency of our algorithms, (b) showing the benefits of query personalization, and (c) providing insight as to the appropriateness of the proposed ranking functions.
Lecture Notes in Computer Science, 2006
Libraries, museums, and other organizations make their electronic contents available to a growing... more Libraries, museums, and other organizations make their electronic contents available to a growing number of users on the Web. A large fraction of the information published is stored in structured or semi-structured form. However, most users have no specific knowledge of schemas or structured query languages for accessing information stored in (relational or XML) databases. Under these circumstances, the need
Proceedings of the 11th international conference on Extending database technology Advances in database technology - EDBT '08, 2008
In the classical database world, information access has been based on a paradigm that involves st... more In the classical database world, information access has been based on a paradigm that involves structured, schema-aware, queries and tabular answers. In the current environment, however, where information prevails in most activities of society, serving people, applications, and devices in dramatically increasing numbers, this paradigm has proved to be very limited. On the query side, much work has been done on moving towards keyword queries over structured data. In our previous work, we have touched the other side as well, and have proposed a paradigm that generates entire databases in response to keyword queries. In this paper, we continue in the same direction and propose synthesizing textual answers in response to queries of any kind over structured data. In particular, we study the transformation of a dynamically-generated logical database subset into a narrative through a customizable, extensible, and templatebased process. In doing so, we exploit the structured nature of database schemas and describe three generic translation modules for different formations in the schema, called unary, split, and join modules. We have implemented the proposed translation procedure into our own database front end and have performed several experiments evaluating the textual answers generated as several features and parameters of the system are varied. We have also conducted a set of experiments measuring the effectiveness of such answers on users. The overall results are very encouraging and indicate the promise that our approach has for several applications.
2007 IEEE 23rd International Conference on Data Engineering, 2007
As a large fraction of available information resides in databases, the need for facilitating acce... more As a large fraction of available information resides in databases, the need for facilitating access for the large majority of users becomes increasingly more important. Précis queries are free-form queries that generate entire multirelation databases, which are logical subsets of existing ones. A logical subset contains not only items directly related to the given query selections but also items implicitly related to them in various ways with the purpose of providing to the user much greater insight into the original data. This paper is concerned with the definition and generation of logical database subsets based on précis queries under a generalized perspective that removes several restrictions of previous work and handles queries containing multiple terms combined using the operators AN D, OR, and NOT .
Proceedings of the 2010 international conference on Management of data - SIGMOD '10, 2010
We study recommendations in applications where there are temporal patterns in the way items are c... more We study recommendations in applications where there are temporal patterns in the way items are consumed or watched. For example, a student who has taken the Advanced Algorithms course is more likely to be interested in Convex Optimization, but a student who has taken Convex Optimization need not be interested in Advanced Algorithms in the future. Similarly, a person who
Proceedings of the fourth ACM international conference on Web search and data mining - WSDM '11, 2011
Abstract We examine the creation of a tag cloud for exploring and understanding a set of objects ... more Abstract We examine the creation of a tag cloud for exploring and understanding a set of objects (eg, web pages, documents). In the first part of our work, we present a formal system model for reasoning about tag clouds. We then present metrics that capture the structural properties of a tag cloud, and we briefly present a set of tag selection algorithms that are used in current sites (eg, del. icio. us, Flickr, Technorati) or that have been described in recent work. In order to evaluate the results of these algorithms, we devise a novel ...
Proceedings of the 2012 international conference on Management of Data - SIGMOD '12, 2012
In this demonstration we present a preference-aware relational query answering system, termed Pre... more In this demonstration we present a preference-aware relational query answering system, termed PrefDB. The key novelty of PrefDB is the use of an extended relational data model and algebra that allow expressing different flavors of preferential queries. Furthermore, unlike existing approaches that either treat the DBMS as a black box or require modifications of the database core, PrefDB's hybrid implementation enables operator-level query optimizations without being obtrusive to the database engine. We showcase the flexibility and efficiency of PrefDB using PrefDBAdmin, a graphical tool that we have built aiming at assisting application designers in the task of building, testing and tuning queries with preferences.
Proceedings of the international conference on Web search and web data mining - WSDM '08, 2008
Page 1. Can Social Bookmarking Improve Web Search? ... Our dataset represents about forty million... more Page 1. Can Social Bookmarking Improve Web Search? ... Our dataset represents about forty million bookmarks from the social bookmarking site del.icio.us. ...
Proceedings of the 35th SIGMOD international conference on Management of data - SIGMOD '09, 2009
Abstract Special-purpose social sites can offer valuable services to well-defined, closed, commun... more Abstract Special-purpose social sites can offer valuable services to well-defined, closed, communities, eg, in a university or in a corporation. The purpose of this demo is to show the challenges, special features and potential of a focused social system in action through CourseRank, a course evaluation and planning social system.
Proceedings of the 12th International Conference on Extending Database Technology Advances in Database Technology - EDBT '09, 2009
Abstract In this demo, we show data clouds that summarize the results of keyword searches over st... more Abstract In this demo, we show data clouds that summarize the results of keyword searches over structured data. Data clouds provide insight into the database contents, hints for query modification and refinement and can lead to serendipitous discoveries of diverse results. In this demo paper:
Proceedings of the 12th International Conference on Extending Database Technology Advances in Database Technology - EDBT '09, 2009
Abstract Keyword searches are attractive because they facilitate users searching structured datab... more Abstract Keyword searches are attractive because they facilitate users searching structured databases. On the other hand, tag clouds are popular for navigation and visualization purposes over unstructured data because they can highlight the most significant concepts and hidden relationships in the underlying content dynamically. In this paper, we propose coupling the flexibility of keyword searches over structured data with the summarization and navigation capabilities of tag clouds to help users access a database. We propose using ...
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Papers by Georgia Koutrika