Contributions in Merlin

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Traditional semantic web query languages support a logic-based access to the semantic web. They offer a retrieval (or reasoning) of data based on facts. On the traditional web and in databases, however, exact querying often provides an incomplete answer as queries are overspecified or the mix of multiple ontologies/modelling differences requires “interpretational flexibility.” This paper introduces iRDQL – a semantic web query language with support for similarity joins. It is an extension to RDQL that enables the user to query for similar resources in an ontology. A similarity measure is used to determine the degree of similarity between two semantic web resources. Similar resources are ranked by their similarity and returned to the user. We show how iRDQL allows to extend the reach of a query by finding additional results. We quantitatively evaluated one measure of SimPack – our library of similarity measures for the use in ontologies – for its usefulness in iRDQL within the context of an OWL-S semantic web service retrieval test collection. Initial results of using iRDQL indicate that it is indeed useful for extending the reach of the query and that it is able to improve recall without overly sacrificing precision.

Requirements standards and textbooks typically classify requirements into functional requirements on the one hand and attributes or non-functional requirements on the other hand. In this classification, requirements given in terms of required operations and/or data are considered to be functional, while performance requirements and quality requirements (such as requirements about security, reliability, maintainability, etc.) are classified as nonfunctional. In this paper, we present arguments why this notion of non-functional requirements is flawed and present a new classification of requirements which is based on four facets: kind (e.g. function, performance, or constraint), representation (e.g. operational, quantitative or qualitative), satisfaction (hard or soft), and role (e.g. prescriptive or assumptive). We define the facets, discuss typical combinations of facets and argue why such a faceted classification of requirements is better than the traditional notion of functional and non-functional requirements.

This paper analyzes a sequential game where firms decide about outsourcing the production of a non-specific input good to an imperfectly competitive input market. We apply the taxonomy of business strategies introduced by Fudenberg and Tirole (1984) to characterize the different equilibria and find that outsourcing generally softens competition in the final product market. If firms anticipate the impact of their outsourcing decisions on input prices, there may be equilibria where firms outsource so as to collude or to raise rivals’ costs. We illustrate our analysis using a linear Cournot model.

Im Tourismus erschließen mobile Kommunikationsgeräte das Potential, „flüchtige Communities“ bei der Kommunikation und bei der Organisation von Reisen mit mobilen Geräten zu unterstützen. In diesem Artikel werden der FlashTourism-Prototyp vorgestellt und die Ergebnisse der Nutzerevaluation diskutiert. Die Unterstützung der profilbasierten Suche nach anderen interessanten Reisenden und die abgestuften Kommunikationsmöglichkeiten wurden gut akzeptiert. Die Publikation von Reiseplanungsinformationen wurde zurückhaltender beurteilt, weil sie die Akteure zu stark bindet. Wir schließen daraus, dass bei flüchtigen Reise-Communities die abgestufte, teilweise unscharfe Bereitstellung von persönlichen Daten eine wesentliche Voraussetzung für die Akzeptanz ist.

We develop and apply a new method for estimating the economic benefits of an environmental amenity. The method is based upon the notion of estimating the derived demand for a privately traded option to utilize an open access good. In particular, the demand for state fishing licenses is used to infer the benefits of recreational fishing. Using panel data on state fishing license sales and prices for the continental United States over a 15-year period, combined with data on substitute prices and demographic variables, a license demand function is estimated with instrumental variable procedures to allow for the potential endogeneity of administered prices. The econometric results lead to estimates of the benefits of a fishing license, and subsequently to the expected benefits of a recreational fishing day. In contrast with previous studies, which have utilized travel cost or hypothetical market methods, our approach provides estimates that are directly comparable across geographic areas. Our findings show substantial variation in the value of a recreational fishing day across geographic areas in the United States. This suggests that current practice of using benefits estimates from one part of the country in national or regional analyses may lead to substantial bias in benefits estimates.

This paper investigates the outcome of ageing on taxes and hospitalisation of the elderly using panel data on 23 Swedish county councils 1980–1999. We test two hypotheses; whether a larger share of elderly has no negative effect on bed days per elderly person and no positive effect on tax rates. We reject the first hypothesis but fail to reject the second hypothesis. Further we cannot reject the hypothesis of a unitary elasticity of the share of elderly on bed days per elderly person. These results imply that the old bear the entire cost of adjustment when the population grows older.

When integrating data from autonomous sources, exact matches of data items that represent the same real world object often fail due to a lack of common keys. Yet in many cases structural information is available and can be used to match such data. As a running example we use residential address information. Addresses are hierarchical structures and are present in many databases. Often they are the best, if not only, relationship between autonomous data sources. Typically the matching has to be approximate since the representations in the sources differ.We propose pq-grams to approximately match hierarchical information from autonomous sources. We define the pq-gram distance between ordered labeled trees as an effective and efficient approximation of the well-known tree edit distance. We analyze the properties of the pq-gram distance and compare it with the edit distance and alternative approximations. Experiments with synthetic and real world data confirm the analytic results and the scalability of our approach.