453 research outputs found

    From Causes for Database Queries to Repairs and Model-Based Diagnosis and Back

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    In this work we establish and investigate connections between causes for query answers in databases, database repairs wrt. denial constraints, and consistency-based diagnosis. The first two are relatively new research areas in databases, and the third one is an established subject in knowledge representation. We show how to obtain database repairs from causes, and the other way around. Causality problems are formulated as diagnosis problems, and the diagnoses provide causes and their responsibilities. The vast body of research on database repairs can be applied to the newer problems of computing actual causes for query answers and their responsibilities. These connections, which are interesting per se, allow us, after a transition -inspired by consistency-based diagnosis- to computational problems on hitting sets and vertex covers in hypergraphs, to obtain several new algorithmic and complexity results for database causality.Comment: To appear in Theory of Computing Systems. By invitation to special issue with extended papers from ICDT 2015 (paper arXiv:1412.4311

    SIP Draft Specification

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    A Submission Information Package (SIP) is defined in the OAIS standard1 as an Information Package that is delivered by the Producer to the OAIS for use in the construction or update of one or more AIPs and/or the associated Descriptive Information. Many different SIP formats are used all over the world and unfortunately there is currently no central format for a SIP which would cover all individual national and business needs identified in the E-ARK Report on Available Best Practices. Therefore, the main objective of this report is to describe a draft SIP specification for the E-ARK project – give an overview of the structure and main metadata elements for E-ARK SIP and provide initial input for the technical implementations of E-ARK ingest tools. The target group of this work are E-ARK project partners as well as all other archival institutions and software providers creating or updating their SIP format specifications. This report provides an overview of: • The general structure for submission information packages. This report explains how the E-ARK SIP is constructed by following the common rules for all other (archival, dissemination) information packages. • The SIP METS Profile. We provide a detailed overview of metadata sections and the metadata elements in these sections. The table with all metadata elements could possibly be of interest to technical stakeholders who wish to continue with the more detailed work of the E-ARK SIP implementation later. Two examples with different kinds of content (MoReq2010, SIARD-E) following the common structure for EARK submission information package can be found in the appendixes to this report

    Best Practice:SIP specification, records export requirements, transfer and ingest

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    This report provides an overview of the current situation of the digital archiving best practices. Special attention is placed on archival ingest workflows, submission information package formats used for transfer and ingest of digital objects and their metadata. Records export best practices are covered as well. The report consists of the following parts: • introduction; • description of the methods used for the analysis; • overview of the results with short descriptions of practices, standards and tools; • recommendations for the E-ARK project; • appendices (the survey questions, an assessment of the interviewed stakeholders, the questions from the qualitative interview and a terminology list). The study concentrates on the following topics from the archival workflow: • Records export (Pre-Ingest workflow steps); • Steps in Ingest workflow; • Submission information packages (SIP) used. Highlighted points of this best practice report for E-ARK work are: • One high-level (pre-) ingest workflow is proposed in section 4 which consists of 4 phases of the PAIMAS methodology, but several existing workflow parts must be examined more deeply to include the common steps to the E-ARK archiving workflow; • E-ARK needs to develop detailed and commonly understood requirements for the records export process which include procedures for data selection, extraction, metadata mapping, validation and quality control as these are currently lacking; • One high-level SIP structure is proposed in section 4. (Recommendation for further work), but several existing SIP physical and logical structures must be examined more deeply to include the common aspects of formats used at archives into the E-ARK SIP specification

    Seventh Biennial Report : June 2003 - March 2005

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    Internet based molecular collaborative and publishing tools

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    The scientific electronic publishing model has hitherto been an Internet based delivery of electronic articles that are essentially replicas of their paper counterparts. They contain little in the way of added semantics that may better expose the science, assist the peer review process and facilitate follow on collaborations, even though the enabling technologies have been around for some time and are mature. This thesis will examine the evolution of chemical electronic publishing over the past 15 years. It will illustrate, which the help of two frameworks, how publishers should be exploiting technologies to improve the semantics of chemical journal articles, namely their value added features and relationships with other chemical resources on the Web. The first framework is an early exemplar of structured and scalable electronic publishing where a Web content management system and a molecular database are integrated. It employs a test bed of articles from several RSC journals and supporting molecular coordinate and connectivity information. The value of converting 3D molecular expressions in chemical file formats, such as the MOL file, into more generic 3D graphics formats, such as Web3D, is assessed. This exemplar highlights the use of metadata management for bidirectional hyperlink maintenance in electronic publishing. The second framework repurposes this metadata management concept into a Semantic Web application called SemanticEye. SemanticEye demonstrates how relationships between chemical electronic articles and other chemical resources are established. It adapts the successful semantic model used for digital music metadata management by popular applications such as iTunes. Globally unique identifiers enable relationships to be established between articles and other resources on the Web and SemanticEye implements two: the Document Object Identifier (DOI) for articles and the IUPAC International Chemical Identifier (InChI) for molecules. SemanticEye’s potential as a framework for seeding collaborations between researchers, who have hitherto never met, is explored using FOAF, the friend-of-a-friend Semantic Web standard for social networks

    Data sharing in DHT based P2P systems

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    International audienceThe evolution of peer-to-peer (P2P) systems triggered the building of large scale distributed applications. The main application domain is data sharing across a very large number of highly autonomous participants. Building such data sharing systems is particularly challenging because of the "extreme" characteristics of P2P infrastructures: massive distribution, high churn rate, no global control, potentially untrusted participants... This article focuses on declarative querying support, query optimization and data privacy on a major class of P2P systems, that based on Distributed Hash Table (P2P DHT). The usual approaches and the algorithms used by classic distributed systems and databases forproviding data privacy and querying services are not well suited to P2P DHT systems. A considerable amount of work was required to adapt them for the new challenges such systems present. This paper describes the most important solutions found. It also identies important future research trends in data management in P2P DHT systems

    Security and Privacy Enhancing Multi-Cloud Architectures

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    Security challenges are still among the biggest obstacles when considering the adoption of cloud services. This triggered a lot of research activities, resulting in a quantity of proposals targeting the various cloud security threats. Alongside with these security issues, the cloud paradigm comes with a new set of unique features, which open the path toward novel security approaches, techniques, and architectures. This paper provides a survey on the achievable security merits by making use of multiple distinct clouds simultaneously. Various distinct architectures are introduced and discussed according to their security and privacy capabilities and prospects

    Information Technology and Lawyers. Advanced Technology in the Legal Domain, from Challenges to Daily Routine

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