Now showing items 1-20 of 30

    • Beyond OWL 2 QL in OBDA: Rewritings and approximations 

      Botoeva E; Calvanese D; Santarelli V; Fabio Savo D; Solimando A; Xiao G (AAAI, 2016)
      Ontology-based data access (OBDA) is a novel paradigm facilitating access to relational data, realized by linking data sources to an ontology by means of declarative mappings. DL-LiteR, which is the logic underpinning the ...
    • Building an FHIR Ontology based Data Access Framework with the OHDSI Data Repositories 

      Jiang G; Xiao G; Kiefer RC; Prod'hommeaux E; Solbrig HR (AIMA, 2017)
    • Cost-Driven Ontology-Based Data Access 

      Lanti D; Xiao G; Calvanese D (Springer, 2017)
      SPARQL query answering in ontology-based data access (OBDA) is carried out by translating into SQL queries over the data source. Standard translation techniques try to transform the user query into a union of conjunctive ...
    • Developing A Semantic Web-based Framework for Executing the Clinical Quality Language Using FHIR 

      Jiang G; Prud’Hommeaux E; Xiao G; Solbrig HR (CEUR-WS.org, 2017)
      The Clinical Quality Language (CQL) is a HL7 specification, aiming to provide a human-readable language to define clinical quality measures and decision support rules while it makes logic expressions independent of any ...
    • Efficient Ontology-Based Data Integration with Canonical IRIs 

      Xiao G; Hovland D; Bilidas D; Rezk M; Giese M; Calvanese D (Springer, 2018)
      In this paper, we study how to efficiently integrate multiple relational databases using an ontology-based approach. In ontology-based data integration (OBDI) an ontology provides a coherent view of multiple databases, and ...
    • An Evaluation of {VIG} with the {BSBM} Benchmark 

      Lanti D; Xiao G; Calvanese D (CEUR, 2016)
      We present an experimental evaluation of VIG, a data scaler for OBDA benchmarks. Data scaling is a relatively recent approach, proposed in the database community, that allows for scaling an input data instance to $s$ times ...
    • Expressivity and Complexity of MongoDB Queries 

      Botoeva E; Calvanese D; Cogrel B; Xiao G (Schloss Dagstuhl - Leibniz-Zentrum für Informatik, 2018)
      In this paper, we consider MongoDB, a widely adopted but not formally understood database system managing JSON documents and equipped with a powerful query mechanism, called the aggregation framework. We provide a clean ...
    • Fast and Simple Data Scaling for OBDA Benchmarks 

      Lanti D; Xiao G; Calvanese D (CEUR Electronic Workshop Proceedings, 2016)
      In this paper we describe VIG, a data scaler for OBDA benchmarks. Data scaling is a relatively recent approach, proposed in the database community, that allows for quickly scaling an input data instance to $n$ times its ...
    • Formalizing MongoDB Queries 

      Botoeva E; Calvanese D; Cogrel B; Xiao G (CEUR-WS.org, 2017)
      In this paper, we report on our ongoing work in which we formalize MongoDB, a widely adopted document database system managing complex (tree structured) values represented in a JSON-based data model, equipped with a powerful ...
    • How to Stay Ontop of Your Data: Databases, Ontologies and More 

      Calvanese D; Cogrel B; Komla-Ebri S; Lanti D; Rezk M; Xiao G (Springer, 2015)
      Ontop is an Ontology Based Data Access system allowing users to access a relational database through a conceptual layer provided by an ontology. In this demo, we use the recently developed NPD benchmark (+4~billion triples) ...
    • Inter-organizational Success Factors: A Cause and Effect Model 

      Krathu W; Pichler C; Xiao G; Neidhardt J; Zapletal M; Werthner H; Huemer C (2015)
      Inter-organizational systems form the basis for successful business collaboration in the Internet and B2B e-commerce era. To properly design and manage such systems one needs to understand the structure and dynamics of the ...
    • Metric Temporal Logic for Ontology-Based Data Access over Log Data 

      Calvanese D; Guzel Kalaycı E; Ryzhikov V; Xiao G; Zakharyaschev M (IJCAI Workshop 40, 2016)
      We present a new metric temporal logic HornMTL over dense time and its datalog extension datalogMTL. The use of datalogMTL is demonstrated in the context of ontology-based data access over meteorological data. We show ...
    • The NPD Benchmark for OBDA Systems 

      Lanti D; Rezk M; Slusnys M; Xiao G; Calvanese D (CEUR Electronic Workshop Proceedings, 2014)
      In Ontology-Based Data Access (OBDA), queries are posed over a high-level conceptual view, and then translated into queries over a potentially very large (usually relational) data source. The ontology is connected to the ...
    • The NPD benchmark: Reality check for OBDA systems 

      Lanti D; Rezk M; Xiao G; Calvanese D (OpenProceedings.org, 2015)
      In the last decades we moved from a world in which an enterprise had one central database - rather small for todays' standards - to a world in which many different - and big - databases must interact and operate, providing ...
    • OBDA Beyond Relational DBs: A Study for MongoDB 

      Botoeva E; Calvanese D; Cogrel B; Rezk M; Xiao G (CEUR Workshop Proceedings, 2016)
      The database landscape has been significantly diversified during the last decade, resulting in the emergence of a variety of non-relational (also called NoSQL) databases, e.g., XML and JSON-document databases, key-value ...
    • OBDA Over Non-Relational Databases 

      Botoeva E; Calvanese D; Cogrel B; Rezk M; Xiao G (CEUR Workshop Proceedings, 2016)
      The database landscape has been significantly diversified during the last decade, resulting in the emergence of a variety of non-relational (also called NoSQL) databases, e.g., XML and JSON-document databases, key-value ...
    • OBDA with the Ontop Framework 

      Calvanese D; Cogrel B; Guzel Kalayci E; Komla Ebri S; Kontchakov R; Lanti D; Rezk M; Rodriguez-Muro M; Xiao G (Curran, 2015)
      Ontology-based data access (OBDA) has become a popular paradigm for accessing data stored in legacy sources using Semantic Web technologies. In the OBDA setting, users access the data through a conceptual layer, which ...
    • Ontology Based Data Access in Statoil 

      Kharlamov E; Hovland D; Skjæveland MG; Bilidas D; Jiménez-Ruiz E; Xiao G; Soylu A; Lanti D; Rezk M; Zheleznyakov D; Giese M; Lie H; Ioannidis Y; Kotidis Y; Koubarakis M; Waaler A (2017)
      Ontology Based Data Access (OBDA) is a prominent approach to query databases which uses an ontology to expose data in a conceptually clear manner by abstracting away from the technical schema-level details of the underlying ...
    • Ontology-Based Access To Temporal Data With Ontop: A Framework Proposal 

      Güzel Kalayci E; Brandt S; Calvanese D; Ryzhikov V; Xiao G; Zakharyaschev M (2019)
      Predictive analysis gradually gains importance in industry. For instance, service engineers at Siemens diagnostic centres unveil hidden knowledge in huge amounts of historical sensor data and use this knowledge to improve ...
    • Ontology-Based Data Access with a Horn Fragment of Metric Temporal Logic 

      Brandt S; Güzel Kalaycı E; Kontchakov R; Ryzhikov V; Xiao G; Zakharyaschev M (AAAI Press, 2017)
      We advocate datalogMTL, a datalog extension of a Horn fragment of the metric temporal logic MTL, as a language for ontology-based access to temporal log data. We show that datalogMTL is EXPSPACE-complete even with punctual ...