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Kontopoulos E.,Aristotle University of Thessaloniki | Bassiliades N.,Aristotle University of Thessaloniki | Governatori G.,NICTA | Antoniou G.,FORTH
International Journal on Semantic Web and Information Systems | Year: 2011

Defeasible logic is a non-monotonic formalism that deals with incomplete and conflicting information, whereas modal logic deals with the concepts of necessity and possibility. These types of logics play a significant role in the emerging Semantic Web, which enriches the available Web information with meaning, leading to better cooperation between end-users and applications. Defeasible and modal logics, in general, and, particularly, deontic logic provide means for modeling agent communities, where each agent is characterized by its cognitive profile and normative system, as well as policies, which define privacy requirements, access permissions, and individual rights. Toward this direction, this article discusses the extension of DR-DEVICE, a Semantic Web-aware defeasible reasoner, with a mechanism for expressing modal logic operators, while testing the implementation via deontic logic operators, concerned with obligations, permissions, and related concepts. The motivation behind this work is to develop a practical defeasible reasoner for the Semantic Web that takes advantage of the expressive power offered by modal logics, accompanied by the flexibility to define diverse agent behaviours. A further incentive is to study the various motivational notions of deontic logic and discuss the cognitive state of agents, as well as the interactions among them. Copyright © 2011, IGI Global. Source


Angles R.,University of Talca | Angles R.,VU University Amsterdam | Boncz P.,CWI | Larriba-Pey J.,Polytechnic University of Catalonia | And 7 more authors.
SIGMOD Record | Year: 2014

The Linked Data Benchmark Council (LDBC) is an EU project that aims to develop industry-strength benchmarks for graph and RDF data management systems. It includes the creation of a non-profit LDBC organization, where industry players and academia come together for managing the development of benchmarks as well as auditing and publishing official results. We present an overview of the project including its goals and organization, and describe its process and design methodology for benchmark development. We introduce so-called "choke-point" based benchmark development through which experts identify key technical challenges, and introduce them in the benchmark workload. Finally, we present the status of two benchmarks currently in development, one targeting graph data management systems using a social network data case, and the other targeting RDF systems using a data publishing case. Source


Nikolov N.,Sintef | Rossini A.,Sintef | Kritikos K.,FORTH
Procedia Computer Science | Year: 2015

Domain-specific languages (DSLs) are high-level software languages representing concepts in a particular domain. In real-world scenarios, it is common to adopt multiple DSLs to solve different aspects of a specific problem. As any other software artefact, DSLs evolve independently in response to changing requirements, which leads to two challenges. First, the concepts from the DSLs have to be integrated into a single language. Second, models that conform to an old version of the language have to be migrated to conform to its current version. In this paper, we discuss how we tackled the challenge of integrating the DSLs that comprise the Cloud Application Modelling and Execution Language (CAMEL) by leveraging upon Eclipse Modeling Framework (EMF) and Object Constraint Language (OCL). Moreover, we propose a solution to the challenge of persisting and automatically migrating CAMEL models based on Connected Data Objects (CDO) and Edapt. © 2015 The Authors. Source


Domaschka J.,University of Ulm | Kritikos K.,FORTH | Rossini A.,Sintef
Communications in Computer and Information Science | Year: 2015

The PaaSage project aims at facilitating the specification and execution of cloud-based applications by leveraging upon model-driven engineering (MDE) techniques and methods, and by exploiting multiple cloud infrastructures and platforms. Models are frequently specified using domain-specific languages (DSLs), which are tailored to a specific domain of concern. In order to cover the necessary aspects of the specification and execution of multi-cloud applications, PaaSage encompasses a family of DSLs called Cloud Application Modelling and Execution Language (CAMEL). In this paper, we present one DSL within this family, namely the Scalability Rules Language (SRL), which can be regarded as a first step towards a generic language for specifying scalability rules for multicloud applications. © Springer International Publishing Switzerland 2015. Source


Sfaelou S.,University of Patras | Raptis D.,University of Patras | Dracopoulos V.,FORTH | Lianos P.,University of Patras
RSC Advances | Year: 2015

An inorganic solar cell was constructed using a thin compact supporting layer of titania with BiOI nanoflakes as a functional material, a Pt/FTO cathode and a I3 -/I- redox electrolyte. The efficiency of the cell was 1.03% but this leaves a lot of ground for improvement, which is mainly expected to come from the optimization of the BiOI nanostructure. © The Royal Society of Chemistry. Source

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