Virtual Knowledge Graphs: An Overview of Systems and Use Cases

Xiao, Guohui; Ding, Linfang; Cogrel, Benjamin; Calvanese, Diego

doi:10.1162/dint_a_00011

Cited by 112 publications

(69 citation statements)

References 60 publications

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“…As I is a model of T and A, there is a homomorphism h : q → I. Then h(y i ) ∈ T I , and so P h(y i ) holds in Π Q (A), for every i ≤ n (by rule (7) and the definition of I). We claim that h(x) is an F-node in Π Q (A), and so G holds in Π Q (A) by rule (6).…”

Section: Datalog Rewritability Of Omqs With a 1-cqmentioning

confidence: 99%

“…Answering various types of queries mediated by a description logic (DL) ontology has been known as an important reasoning problem in knowledge representation since the early 1990s [1]. The proliferation of DLs and their applications [2,3], the development of the (DL-underpinned) Web Ontology Language OWL 1 , and especially the paradigm of ontology-based data access (OBDA) [4,5,6] (proposed in the mid 2000s and recently nicknamed the virtual knowledge graph paradigm (VKG) [7]), have made theory and practice of answering ontology-mediated queries (OMQs) a hot research area lying at the crossroads of Knowledge Representation and Reasoning, Semantic Technologies and the Semantic Web, Knowledge Graphs, and Database Theory and Technologies.…”

Section: Introductionmentioning

confidence: 99%

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A Data Complexity and Rewritability Tetrachotomy of Ontology-Mediated Queries with a Covering Axiom

Gerasimova

Kikot

Kurucz

et al. 2020

Proceedings of the Seventeenth International Conference on Principles of Knowledge Representation and Reasoning

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Aiming to understand the data complexity of answering conjunctive queries mediated by an axiom stating that a class is covered by the union of two other classes, we show that deciding their first-order rewritability is PSPACE-hard and obtain a number of sufficient conditions for membership in AC0, L, NL, and P. Our main result is a complete syntactic AC0/NL/P/CONP tetrachotomy of path queries under the assumption that the covering classes are disjoint.

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Section: Datalog Rewritability Of Omqs With a 1-cqmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

A Data Complexity and Rewritability Tetrachotomy of Ontology-Mediated Queries with a Covering Axiom

Gerasimova

Kikot

Kurucz

et al. 2020

Proceedings of the Seventeenth International Conference on Principles of Knowledge Representation and Reasoning

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“…At the time of the migration, the conversion tool used a recent OMOP schema version (5.x). Finally, in order to demonstrate that our pipeline is not dependent on a particular data aggregation service, we chose to perform the OMOP transformation to RDF with Stardog's Virtual Graph 39 . This service instantiated the Synthea data in the OMOP PostgreSQL database as concise triples.…”

Section: Synthea Pipeline Architecturementioning

confidence: 99%

A novel tool for standardizing clinical data in a realism-based common data model

Freedman

Williams

Miller

et al. 2020

Preprint

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Standardizing clinical information in a common data model is important for promoting interoperability and facilitating high quality research. Semantic Web technologies such as Resource Description Framework can be utilized to their full potential when a clinical data model accurately reflects the reality of the clinical situation it describes. To this end, the Open Biomedical Ontologies Foundry provides a set of ontologies that conform to the principles of realism and can be used to create a realism-based clinical data model. However, the challenge of programmatically defining such a model and loading data from disparate sources into the model has not been addressed by pre-existing software solutions. The PennTURBO Semantic Engine is a tool developed at the University of Pennsylvania that works in conjunction with data aggregation software to transform source-specific RDF data into a source-independent, realism-based data model. This system sources classes from an application ontology and specifically defines how instances of those classes may relate to each other. Additionally, the system defines and executes RDF data transformations by launching dynamically generated SPARQL update statements. The Semantic Engine was designed as a generalizable RDF data standardization tool, and is able to work with various data models and incoming data sources. Its human-readable configuration files can easily be shared between institutions, providing the basis for collaboration on a standard realismbased clinical data model.

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“…The Virtual Knowledge Graph (VKG) approach, also known in the literature as Ontology-Based Data Access (OBDA) [16,23], has become a popular paradigm for accessing and integrating data sources [24]. In such approach, the data sources, which are normally relational databases, are virtualized through a mapping and an ontology, and presented as a unified knowledge graph, which can be queried by end-users using a vocabulary they are familiar with.…”

Section: Introductionmentioning

confidence: 99%

“…In addition to the research groups, Ontop is also backed by a commercial company, Ontopic s.r.l., born in April 2019. Ontop has been adopted in many academic and industrial projects [24]. We discuss the community effort and the adoption of Ontop in Section 5.…”

Section: Introductionmentioning

confidence: 99%