Stefan Mandl

Understanding casual-leisure information needs: a diary study in the context of television viewing

In this paper, we provide novel research on information behaviour and information needs in the context of television viewing. We conducted a diary study of a heterogeneous population (n=38), in the non-work related activity of watching television, and we received 381 responses. From the collected responses, we used a bottom-up approach to generate coding schemes for the needs and reasons given for those needs, respectively. Subsequently, 4 coders tested the coherency of the coding schemes by coding 50 random needs and reasons, and this revealed a large consistency in the use of the schemes. Our findings reveal important aspects of information behaviour in the context of television viewing and show how the characteristics of information needs can be different in leisure or non-work situations. We also found that contextual factors are very influential in relation to the needs and reasons. With these findings we provide important knowledge in relation to future television information systems design.

Complex preference queries supporting spatial applications for user groups

Our demo application demonstrates a personalized location-based web application using Preference SQL that allows single users as well as groups of users to find accommodations in Istanbul that satisfy both hard constraints and user preferences. The application assists in defining spatial, numerical, and categorical base preferences and composes complex preference statements in an intuitive fashion. Unlike existing location-based services, the application considers spatial queries as soft instead of hard constraints to determine the best matches which are finally presented on a map. The underlying Preference SQL framework is implemented on top of a database, therefore enabling a seamless application integration with standard SQL back-end systems as well as efficient and extensible preference query processing.

What's on tonight: user-centered and situation-aware proposals for TV programmes

This paper presents an approach to exploit free text descriptions of TV programmes as available from EPG data sets for a TV recommender system that takes the content of programmes into account. The paper focuses on the natural language understanding problem underlying the analysis of free text descriptions and on methods of classifying free text descriptions with respect to a natural language user query. We close with an evaluation of user acceptance and a discussion of future work.

Design and Implementation of a Framework for Context-Aware Preference Queries

In this paper we present a framework for a novel kind of context-aware preference query composition whereby queries for the Preference SQL system are created. We choose a commercial e-business platform for outdoor activities as a use case and develop a context model for this domain within our framework. The suggested model considers explicit user input, domain-specific knowledge, contextual knowledge and location-based sensor data in a comprehensive approach. Aside from the theoretical background of preferences, the optimization of preference queries and our novel generator based model we give special attention to the aspects of the implementation and the practical experiences. We provide a sketch of the implementation and summarize our user studies which have been done in a joint project with an industrial partner.

Multi-context systems with activation rules

Multi-Context Systems provide a formal basis for the integration of knowledge from different knowledge sources. Yet, it is easy to conceive of applications where not all knowledge sources may be used together all the time. We present a natural extension of Multi-Context Systems by adding the notion of activation rules that allows modeling the applicability or relevance of contexts depending on beliefs in the various contexts and their mutual dependencies. We give a short account on possible consequence relations for Multi-Context System with Activation Rules and discuss a potential application in information retrieval.

Evolution of Agent Coordination in an Asynchronous Version of the Predator-Prey Pursuit Game

In this paper, we introduce an asynchronous version of the well-known pursuit game. The validity of past results on the synchronous version of the pursuit game is verified in this new setting by considering five kinds of prey: Still prey, randomly moving prey, avoiding prey, linear prey, and linear prey with switching behavior. Genetic programming is used to evolve teams of predators whose capture rates are compared to that of a greedy strategy. Task assignment is used as an explicit means of coordination in the evolved teams of predators. We conclude that evolved teams with explicit coordination outperform greedy non-cooperative strategies when more competent prey is faced.

Static preference models for options with dynamic extent

Models of user preferences are an important resource to improve the user experience of recommender systems. Using user feedback static preference models can be adapted over time. Still, if the options to choose from themselves have temporal extent, dynamic preferences have to be taken into account even when answering a single query. In this paper we propose that static preference models could be used in such situations by identifying an appropriate set of features.

An agent-based approach to correctness in databases

When defining the schema of a relational database, integrity constraints are included to describe simple syntactic constraints of correctness that can easily be tested in a centralized way when tuples are inserted, deleted or updated. Complex dependencies may exist between different tuples of a relation. The description of them can be difficult with current formalisms. An example for such an inconsistency is the problem of duplicates, the existence of different tuples describing the same real world entity. Duplicates can occur when one makes typographic or other errors while transferring the representation of a real-world entity to the database. In this paper, we describe a new method to detect dependencies of that kind using continuously active agents that check consistency of a database and propose steps to improve the content of the database.