Odysseas Papapetrou

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Modeling competences is an integral part of many Human Resource (HR) and e-Learning related activities. HR departments use competence descriptions to define requirements needed for performing specific tasks or jobs. The same competences are acquired by employees and applicants by e.g. experience or certifications. Typically, HR departments need to match(More)
Aspect Oriented Programming, a relatively new programming paradigm, earned the scientific community's attention. The paradigm is already evaluated for traditional OOP and component-based software development with remarkable results. However, most of the published work, while of excellent quality, is mostly theoretical or involves evaluation of AOP for(More)
Bloom filters are extensively used in distributed applications, especially in distributed databases and distributed information systems, to reduce network requirements and to increase performance. In this work, we propose two novel Bloom filter features that are important for distributed databases and information systems. First, we present a new approach to(More)
Distributed hash tables (DHTs) are very efficient for querying based on key lookups. However, building huge term indexes, as required for IR-style keyword search, poses a scalability challenge for plain DHTs. Due to the large sizes of document term vocabularies, peers joining the network cause huge amounts of key inserts and, consequently, a large number of(More)
Distributed crawling has shown that it can overcome important limitations of the centralized crawling paradigm. However, the distributed nature of current distributed crawlers is currently not fully utilized. The optimal benefits of this approach are usually limited to the sites hosting the crawler. In this work we describe IPMicra, a distributed location(More)
Bloom filter based algorithms have proven successful as very efficient technique to reduce communication costs of database joins in a distributed setting. However, the full potential of bloom filters has not yet been exploited. Especially in the case of multi-joins, where the data is distributed among several sites, additional optimization opportunities(More)
While traditional data-management systems focus on evaluating single, ad-hoc queries over static data sets in a centralized setting, several emerging applications require (possibly, continuous) answers to queries on dynamic data that is widely distributed and constantly updated. Furthermore, such query answers often need to discount data that is " stale " ,(More)
Mining frequent subgraph patterns in graph databases is a challenging and important problem with applications in several domains. Recently, there is a growing interest in generalizing the problem to <i>uncertain graphs</i>, which can model the inherent uncertainty in the data of many applications. The main difficulty in solving this problem results from the(More)
Software Architectures have evolved considerably over the last decade and, partly also due to the significant progress made in component-based development, have become a major subfield of Software Engineering. The associated field of Architecture Description Languages (ADLs) has also evolved considerably, providing numerous approaches to the formal(More)