Browsing Περιοδικά, εφημερίδες by Author "Γεργατσούλης, Μανώλης"

Now showing items 1-20 of 30

    • Automatic Generation of Crosswalks through CIDOC CRM 

      Μπουντούρη, Λίνα; Γαϊτάνου, Πανωραία; Γεργατσούλης, Μανώλης; Gaitanou, Panorea; Gergatsoulis, Manolis; Bountouri, Lina (2012)
      In this paper, we propose an algorithm that automatically generates crosswalks between metadata schemas. The algorithm exploits the mappings between the schemas and the CIDOC Conceptual Reference Model (CRM), defined as ...

    • The branching-time transformation technique for Chain Datalog programs 

      Γεργατσούλης, Μανώλης; Ροντογιάννης, Παναγιώτης; Gergatsoulis, Manolis; Rondogiannis, Panos (2001)
      The branching-time transformation technique has proven to be an efficient approach for implementing functional programming languages. In this paper we demonstrate that such a technique can also be defined for logic programming ...

    • Defining a semantic mapping of VRA Core 4.0 to the CIDOC conceptual reference model 

      Γεργατσούλης, Μανώλης; Γαϊτάνου, Πανωραία; Gergatsoulis, Manolis; Gaitanou, Panorea (2012)
      In the recent decades, we have witnessed a tremendous proliferation of metadata schemas, particularly in the cultural heritage domain. As a consequence, cultural heritage communities face a growing need to integrate these ...

    • Designing views to efficiently answer real SQL queries 

      Γεργατσούλης, Μανώλης; Αφράτη, Φώτο; Παυλάκη, Βάσια; Chirkova, Rada; Gergatsoulis, Manolis; Afrati, Foto; Pavlaki, Vassia (2005)
      The problem of optimizing queries in the presence of materialized views and the related view-design problem have recently attracted a lot of attention. Significant research results have been reported, and materialized views ...

    • Finding equivalent rewritings in the presence of arithmetic comparisons 

      Γεργατσούλης, Μανώλης; Αφράτη, Φώτο; Παυλάκη, Βάσια; Chirkova, Rada; Afrati, Foto; Pavlaki, Vassia; Gergatsoulis, Manolis (2006)
      The problem of rewriting queries using views has received significant attention because of its applications in a wide variety of data-management problems. For select-project-join SQL (a.k.a. conjunctive) queries and views, ...

    • Incorporating dimensions in XML and DTD 

      Γεργατσούλης, Μανώλης; Σταύρακας, Γιάννης; Καρτέρης, Δ.; Gergatsoulis, Manolis; Stavrakas, Yannis; Karteris, D. (2001)
      In this,paper we investigate various aspects of representing multidimensional information in the frame of the WWW. Multidimensional XML (MXML) is an extension of XML suitable for representing data that assume different ...

    • Interoperability Between Archival and Bibliographic Metadata: an EAD to MODS Crosswalk 

      Μπουντούρη, Λίνα; Γεργατσούλης, Μανώλης; Gergatsoulis, Manolis; Bountouri, Lina (2009)
      In this article we investigate the problem of semantic interoperability between archival and bibliographic metadata used in digital libraries and repositories. We investigate the semantic relationships between two metadata ...

    • Linearisability on datalog programs 

      Γεργατσούλης, Μανώλης; Αφράτη, Φώτο; Toni, F.; Gergatsoulis, Manolis; Afrati, Foto (2003)
      Linear Datalog programs are programs whose clauses have at most one intensional atom in their bodies. We explore syntactic classes of Datalog programs (syntactically non-linear) which turn out to express no more than the ...

    • Mapping cultural metadata schemas to CIDOC conceptual reference model 

      Γεργατσούλης, Μανώλης; Μπουντούρη, Λίνα; Παπαθεοδώρου, Χρήστος; Γαϊτάνου, Πανωραία; Gergatsoulis, Manolis; Gaitanou, Panorea; Bountouri, Lina; Papatheodorou, Christos (2010)
      Managing heterogeneous data is a challenge for cultural heritage institutions as they host and develop various collections with heterogeneous types of material, described by different metadata schemas. In this paper, we ...

    • Modelling the Public Sector Information through CIDOC Conceptual Reference Model 

      Μπουντούρη, Λίνα; Παπαθεοδώρου, Χρήστος; Γεργατσούλης, Μανώλης; Gergatsoulis, Manolis; Bountouri, Lina; Papatheodorou, Christos (2010)
      Nowadays, due to the growing development of eGovernment information systems, there is an increasing need to handle Public Sector Information (PSI) in a homogeneous way. Ontologies are currently a powerful tool to act as ...

    • Multidimensional RDF 

      Γεργατσούλης, Μανώλης; Λιλής, Παντελής Δ.; Gergatsoulis, Manolis; Lilis, Pantelis D. (2005)
      RDF has been proposed by W3C as a metadata model and language for representing information about resources in WWW. In this paper we introduce Multidimensional RDF (or MRDF), as an extension of RDF, suitable for representing ...

    • Multidimensional XPath 

      Γεργατσούλης, Μανώλης; Φουστέρης, Νικόλαος; Σταύρακας, Γιάννης; Gergatsoulis, Manolis; Fousteris, Nikolaos; Stavrakas, Yannis (2008)
      In Web applications it is often required to manipulate information of semistructured nature, which may present variations according to different circumstances. Multidimensional XML (MXML) is an extension of XML suitable ...

    • On rewriting Xpath Queries Using Views 

      Γεργατσούλης, Μανώλης; Αφράτη, Φώτο; Παυλάκη, Βάσια; Chirkova, Rada; Kimelfeld, B.; Sagiv, Y.; Gergatsoulis, Manolis; Afrati, Foto; Pavlaki, Vassia (2009)
      The problem of rewriting a query using a materialized view is studied for a well known fragment of XPath that includes the following three constructs: wildcards, descendant edges and branches. In earlier work, determining ...

    • On solving efficiently the view selection problem under bag-semantics 

      Γεργατσούλης, Μανώλης; Αφράτη, Φώτο; Damigos, M.; Gergatsoulis, Manolis; Afrati, Foto (2009)
      In this paper, we investigate the problem of view selection for workloads of conjunctive queries under bag semantics. In particular we aim to limit the search space of candidate viewsets. In that respect we start delineating ...

    • Ontology-Based Metadata Integration in the Cultural Heritage Domain 

      Στασινοπούλου, Θωμαΐς; Μπουντούρη, Λίνα; Κακάλη, Κωνσταντία; Παπαθεοδώρου, Χρήστος; Λουρδή, Ειρήνη; Γεργατσούλης, Μανώλης; Doerr, Martin; Stasinopoulou, Thomais; Kakali, Constantia; Gergatsoulis, Manolis; Lourdi, Eirini; Bountouri, Lina; Papatheodorou, Christos (2007)
      In this paper, we propose an ontology-based metadata integration methodology for the cultural heritage domain. The proposed real - world approach considers an integration architecture in which CIDOC/CRM ontology acts as a ...

    • Query containment under bag and bag-set semantics 

      Γεργατσούλης, Μανώλης; Αφράτη, Φώτο; Damigos, M.; Gergatsoulis, Manolis; Afrati, Foto (2010)
      Conjunctive queries (CQs) are at the core of query languages encountered in many logic-based research fields such as AI, or database systems. The majority of existing work assumes set semantics but often in real applications ...

    • Query Transformation in a CIDOC CRM Based Cultural Metadata Integration Environment 

      Γεργατσούλης, Μανώλης; Γαϊτάνου, Πανωραία; Μπουντούρη, Λίνα; Παπαθεοδώρου, Χρήστος; Gergatsoulis, Manolis; Gaitanou, Panorea; Bountouri, Lina; Papatheodorou, Christos (2010)
      The wide use of a number of cultural heritage metadata schemas imposes the development of new interoperability techniques that facilitate unified access to cultural resources. In this paper, we focus on the ontology based ...

    • Representing and querying histories of semistructured databases using multidimensional OEM 

      Γεργατσούλης, Μανώλης; Σταύρακας, Γιάννης; Ζαφείρης, Βασίλης; Δουληγέρης, Χρήστος; Gergatsoulis, Manolis; Stavrakas, Yannis; Doulkeridis, Christos; Zafeiris, Vassilis (2004)
      Multidimensional semistructured data (MSSD) are semistructured data that present different facets under different contexts. Context represents alternative worlds, and is expressed by assigning values to a set of user-defined ...

    • Representing changes in XML documents using dimensions 

      Γεργατσούλης, Μανώλης; Σταύρακας, Γιάννης; Gergatsoulis, Manolis; Stavrakas, Yannis (2003)
      In this paper, we present a method for representing the history of XML documents using Multidimensional XML (MXML). We demonstrate how a set of basic change operations on XML documents can be represented in MXML, and show ...

    • Representing time-dependent information in multidimensional XML 

      Γεργατσούλης, Μανώλης; Gergatsoulis, Manolis (2001)
      Multidimensional XML (MXML) is an extension of XML that incorporates dimensions in order to represent in an elegant and concise way context-dependent data, that is, data which can exhibit different variations in value or ...