RDF and Property Graphs Interoperability: Status and Issues
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Semantics Developer's Guide
MarkLogic Server Semantic Graph Developer’s Guide 2 MarkLogic 10 May, 2019 Last Revised: 10.0-8, October, 2021 Copyright © 2021 MarkLogic Corporation. All rights reserved. MarkLogic Server MarkLogic 10—May, 2019 Semantic Graph Developer’s Guide—Page 2 MarkLogic Server Table of Contents Table of Contents Semantic Graph Developer’s Guide 1.0 Introduction to Semantic Graphs in MarkLogic ..........................................11 1.1 Terminology ..........................................................................................................12 1.2 Linked Open Data .................................................................................................13 1.3 RDF Implementation in MarkLogic .....................................................................14 1.3.1 Using RDF in MarkLogic .........................................................................15 1.3.1.1 Storing RDF Triples in MarkLogic ...........................................17 1.3.1.2 Querying Triples .......................................................................18 1.3.2 RDF Data Model .......................................................................................20 1.3.3 Blank Node Identifiers ..............................................................................21 1.3.4 RDF Datatypes ..........................................................................................21 1.3.5 IRIs and Prefixes .......................................................................................22 1.3.5.1 IRIs ............................................................................................22 -
Rdfa in XHTML: Syntax and Processing Rdfa in XHTML: Syntax and Processing
RDFa in XHTML: Syntax and Processing RDFa in XHTML: Syntax and Processing RDFa in XHTML: Syntax and Processing A collection of attributes and processing rules for extending XHTML to support RDF W3C Recommendation 14 October 2008 This version: http://www.w3.org/TR/2008/REC-rdfa-syntax-20081014 Latest version: http://www.w3.org/TR/rdfa-syntax Previous version: http://www.w3.org/TR/2008/PR-rdfa-syntax-20080904 Diff from previous version: rdfa-syntax-diff.html Editors: Ben Adida, Creative Commons [email protected] Mark Birbeck, webBackplane [email protected] Shane McCarron, Applied Testing and Technology, Inc. [email protected] Steven Pemberton, CWI Please refer to the errata for this document, which may include some normative corrections. This document is also available in these non-normative formats: PostScript version, PDF version, ZIP archive, and Gzip’d TAR archive. The English version of this specification is the only normative version. Non-normative translations may also be available. Copyright © 2007-2008 W3C® (MIT, ERCIM, Keio), All Rights Reserved. W3C liability, trademark and document use rules apply. Abstract The current Web is primarily made up of an enormous number of documents that have been created using HTML. These documents contain significant amounts of structured data, which is largely unavailable to tools and applications. When publishers can express this data more completely, and when tools can read it, a new world of user functionality becomes available, letting users transfer structured data between applications and web sites, and allowing browsing applications to improve the user experience: an event on a web page can be directly imported - 1 - How to Read this Document RDFa in XHTML: Syntax and Processing into a user’s desktop calendar; a license on a document can be detected so that users can be informed of their rights automatically; a photo’s creator, camera setting information, resolution, location and topic can be published as easily as the original photo itself, enabling structured search and sharing. -
Mapping Between Digital Identity Ontologies Through SISM
Mapping between Digital Identity Ontologies through SISM Matthew Rowe The OAK Group, Department of Computer Science, University of Sheffield, Regent Court, 211 Portobello Street, Sheffield S1 4DP, UK [email protected] Abstract. Various ontologies are available defining the semantics of dig- ital identity information. Due to the rise in use of lowercase semantics, such ontologies are now used to add metadata to digital identity informa- tion within web pages. However concepts exist in these ontologies which are related and must be mapped together in order to enhance machine- readability of identity information on the web. This paper presents the Social identity Schema Mapping (SISM) vocabulary which contains a set of mappings between related concepts in distinct digital identity ontolo- gies using OWL and SKOS mapping constructs. Key words: Semantic Web, Social Web, SKOS, OWL, FOAF, SIOC, PIMO, NCO, Microformats 1 Introduction The semantic web provides a web of machine-readable data. Ontologies form a vital component of the semantic web by providing conceptualisations of domains of knowledge which can then be used to provide a common understanding of some domain. A basic ontology contains a vocabulary of concepts and definitions of the relationships between those concepts. An agent reading a concept from an ontology can look up the concept and discover its properties and characteristics, therefore interpreting how it fits into that particular domain. Due to the great number of ontologies it is common for related concepts to be defined in separate ontologies, these concepts must be identified and mapped together. Web technologies such as Microformats, eRDF and RDFa have allowed web developers to encode lowercase semantics within XHTML pages. -
An Introduction to RDF
An Introduction to RDF Knowledge Technologies 1 Manolis Koubarakis Acknowledgement • This presentation is based on the excellent RDF primer by the W3C available at http://www.w3.org/TR/rdf-primer/ and http://www.w3.org/2007/02/turtle/primer/ . • Much of the material in this presentation is verbatim from the above Web site. Knowledge Technologies 2 Manolis Koubarakis Presentation Outline • Basic concepts of RDF • Serialization of RDF graphs: XML/RDF and Turtle • Other Features of RDF (Containers, Collections and Reification). Knowledge Technologies 3 Manolis Koubarakis What is RDF? •TheResource Description Framework (RDF) is a data model for representing information (especially metadata) about resources in the Web. • RDF can also be used to represent information about things that can be identified on the Web, even when they cannot be directly retrieved on the Web (e.g., a book or a person). • RDF is intended for situations in which information about Web resources needs to be processed by applications, rather than being only displayed to people. Knowledge Technologies 4 Manolis Koubarakis Some History • RDF draws upon ideas from knowledge representation, artificial intelligence, and data management, including: – Semantic networks –Frames – Conceptual graphs – Logic-based knowledge representation – Relational databases • Shameless self-promotion : The closest to RDF, pre-Web knowledge representation language is Telos: John Mylopoulos, Alexander Borgida, Matthias Jarke, Manolis Koubarakis: Telos: Representing Knowledge About Information Systems. ACM Trans. Inf. Syst. 8(4): 325-362 (1990). Knowledge Technologies 5 Manolis Koubarakis The Semantic Web “Layer Cake” Knowledge Technologies 6 Manolis Koubarakis RDF Basics • RDF is based on the idea of identifying resources using Web identifiers and describing resources in terms of simple properties and property values. -
Linked Data Schemata: Fixing Unsound Foundations
Linked data schemata: fixing unsound foundations. Kevin Feeney, Gavin Mendel Gleason, Rob Brennan Knowledge and Data Engineering Group & ADAPT Centre, School of Computer Science & Statistics, Trinity College Dublin, Ireland Abstract. This paper describes an analysis, and the tools and methods used to produce it, of the practical and logical implications of unifying common linked data vocabularies into a single logical model. In order to support any type of reasoning or even just simple type-checking, the vocabularies that are referenced by linked data statements need to be unified into a complete model wherever they reference or reuse terms that have been defined in other linked data vocabularies. Strong interdependencies between vocabularies are common and a large number of logical and practical problems make this unification inconsistent and messy. However, the situation is far from hopeless. We identify a minimal set of necessary fixes that can be carried out to make a large number of widely-deployed vocabularies mutually compatible, and a set of wider-ranging recommendations for linked data ontology design best practice to help alleviate the problem in future. Finally we make some suggestions for improving OWL’s support for distributed authoring and ontology reuse in the wild. Keywords: Linked Data, Reasoning, Data Quality 1. Introduction One of the central tenets of the Linked Data movement is the reuse of terms from existing well- known vocabularies [Bizer09] when developing new schemata or datasets. The semantic web infrastructure, and the RDF, RDFS and OWL languages, support this with their inherently distributed and modular nature. In practice, through vocabulary reuse, linked data schemata adopt knowledge models that are based on multiple, independently devised ontologies that often exhibit varying definitional semantics [Hogan12]. -
On Blank Nodes
On Blank Nodes Alejandro Mallea1, Marcelo Arenas1, Aidan Hogan2, and Axel Polleres2;3 1 Department of Computer Science, Pontificia Universidad Católica de Chile, Chile Email: {aemallea,marenas}@ing.puc.cl 2 Digital Enterprise Research Institute, National University of Ireland Galway, Ireland Email: {aidan.hogan,axel.polleres}@deri.org 3 Siemens AG Österreich, Siemensstrasse 90, 1210 Vienna, Austria Abstract. Blank nodes are defined in RDF as ‘existential variables’ in the same way that has been used before in mathematical logic. However, evidence suggests that actual usage of RDF does not follow this definition. In this paper we thor- oughly cover the issue of blank nodes, from incomplete information in database theory, over different treatments of blank nodes across the W3C stack of RDF- related standards, to empirical analysis of RDF data publicly available on the Web. We then summarize alternative approaches to the problem, weighing up advantages and disadvantages, also discussing proposals for Skolemization. 1 Introduction The Resource Description Framework (RDF) is a W3C standard for representing in- formation on the Web using a common data model [18]. Although adoption of RDF is growing (quite) fast [4, § 3], one of its core features—blank nodes—has been sometimes misunderstood, sometimes misinterpreted, and sometimes ignored by implementers, other standards, and the general Semantic Web community. This lack of consistency between the standard and its actual uses calls for attention. The standard semantics for blank nodes interprets them as existential variables, de- noting the existence of some unnamed resource. These semantics make even simple entailment checking intractable. RDF and RDFS entailment are based on simple entail- ment, and are also intractable due to blank nodes [14]. -
OGC Testbed-14: Semantically Enabled Aviation Data Models Engineering Report
OGC Testbed-14 Semantically Enabled Aviation Data Models Engineering Report Table of Contents 1. Summary . 4 1.1. Requirements & Research Motivation . 4 1.2. Prior-After Comparison. 4 1.3. Recommendations for Future Work . 5 1.4. What does this ER mean for the Working Group and OGC in general . 6 1.5. Document contributor contact points . 6 1.6. Foreword . 6 2. References . 8 3. Terms and definitions . 9 3.1. Semantics . 9 3.2. Service Description. 9 3.3. Service-Oriented Architecture (SOA) . 9 3.4. Registry . 9 3.5. System Wide Information Management (SWIM) . 9 3.6. Taxonomy . 9 3.7. Web Service . 10 4. Abbreviated Terms . 11 5. Overview . 12 6. Review of Data Models . 13 6.1. Information Exchange Models . 13 6.1.1. Flight Information Exchange Model (FIXM). 13 6.1.2. Aeronautical Information Exchange (AIXM) Model. 13 6.1.3. Weather Information Exchange Model (WXXM) . 14 6.1.4. NASA Air Traffic Management (ATM) Model . 14 6.2. Service description models . 19 6.2.1. Service Description Conceptual Model (SDCM) . 19 6.2.2. Web Service Description Ontological Model (WSDOM). 23 6.2.3. SWIM Documentation Controlled Vocabulary (FAA) . 25 7. Semantic Enablement Approaches . 27 8. Metadata level semantic enablement . 33 8.1. Issues with existing metadata standards . 34 8.1.1. Identification of Resources. 34 8.1.2. Resolvable URI. 34 8.1.3. Multilingual Support . 35 8.1.4. External Resource Descriptions . 35 8.1.5. Controlled Vocabulary Management . 36 8.1.6. Keywords Types . 37 8.1.7. Keyword Labeling Inconsistencies . -
OWL 2 Web Ontology Language XML Serialization W3C Proposed Recommendation 22 September 2009
OWL 2 Web Ontology Language XML Serialization W3C Proposed Recommendation 22 September 2009 OWL 2 Web Ontology Language XML Serialization W3C Proposed Recommendation 22 September 2009 This version: http://www.w3.org/TR/2009/PR-owl2-xml-serialization-20090922/ Latest version: http://www.w3.org/TR/owl2-xml-serialization/ Previous version: http://www.w3.org/TR/2009/CR-owl2-xml-serialization-20090611/ (color-coded diff) Editors: Boris Motik, Oxford University Computing Laboratory Bijan Parsia, University of Manchester Peter F. Patel-Schneider, Bell Labs Research, Alcatel-Lucent Contributors: (in alphabetical order) Sean Bechhofer, University of Manchester Bernardo Cuenca Grau, Oxford University Computing Laboratory Achille Fokoue, IBM Corporation Rinke Hoekstra, University of Amsterdam This document is also available in these non-normative formats: PDF version. Copyright © 2009 W3C® (MIT, ERCIM, Keio), All Rights Reserved. W3C liability, trademark and document use rules apply. Abstract The OWL 2 Web Ontology Language, informally OWL 2, is an ontology language for the Semantic Web with formally defined meaning. OWL 2 ontologies provide classes, properties, individuals, and data values and are stored as Semantic Web documents. OWL 2 ontologies can be used along with information written in RDF, and OWL 2 ontologies themselves are primarily exchanged as RDF documents. The OWL 2 Document Overview describes the overall state of OWL 2, and should be read before other OWL 2 documents. Page 1 of 35 http://www.w3.org/TR/2009/PR-owl2-xml-serialization-20090922/ OWL 2 Web Ontology Language XML Serialization W3C Proposed Recommendation 22 September 2009 This document specifies an XML serialization for OWL 2 that mirrors its structural specification. -
RDF—The Basis of the Semantic Web 3
CHAPTER RDF—The basis of the Semantic Web 3 CHAPTER OUTLINE Distributing Data across the Web ........................................................................................................... 28 Merging Data from Multiple Sources ...................................................................................................... 32 Namespaces, URIs, and Identity............................................................................................................. 33 Expressing URIs in print..........................................................................................................35 Standard namespaces .............................................................................................................37 Identifiers in the RDF Namespace........................................................................................................... 38 Higher-order Relationships .................................................................................................................... 42 Alternatives for Serialization ................................................................................................................. 44 N-Triples................................................................................................................................44 Turtle.....................................................................................................................................45 RDF/XML.............................................................................................................................................. -
XHTML+Rdfa 1.1 - Third Edition Table of Contents
XHTML+RDFa 1.1 - Third Edition Table of Contents XHTML+RDFa 1.1 - Third Edition Support for RDFa via XHTML Modularization W3C Recommendation 17 March 2015 This version: http://www.w3.org/TR/2015/REC-xhtml-rdfa-20150317/ Latest published version: http://www.w3.org/TR/xhtml-rdfa/ Implementation report: http://www.w3.org/2010/02/rdfa/wiki/CR-ImplementationReport Previous version: http://www.w3.org/TR/2014/PER-xhtml-rdfa-20141216/ Previous Recommendation: http://www.w3.org/TR/2013/REC-xhtml-rdfa-20130822/ Editor: Shane McCarron, Applied Testing and Technology, Inc., [email protected] Please check the errata for any errors or issues reported since publication. This document is also available in these non-normative formats: XHTML+RDFa, Diff from Previous Recommendation, Postscript version, and PDF version The English version of this specification is the only normative version. Non-normative translations may also be available. Copyright © 2007-2015 W3C® (MIT, ERCIM, Keio, Beihang). W3C liability, trademark and document use rules apply. Abstract RDFa Core 1.1 [RDFA-CORE [p.61] ] defines attributes and syntax for embedding semantic markup in Host Languages. This document defines one such Host Language. This language is a superset of XHTML 1.1 [XHTML11-2e [p.61] ], integrating the attributes as defined in RDFa Core 1.1. This document is intended for authors who want to create XHTML Family documents that embed rich semantic markup. - 1 - Status of This Document XHTML+RDFa 1.1 - Third Edition Status of This Document This section describes the status of this document at the time of its publication. -
State of the Semantic Web
State of the Semantic Web Ivan Herman, W3C Sunday, 18 May, 2008 (2) > So where are we with the Semantic Web? State of the Semantic Web, Ivan Herman (2) Copyright © 2008, W3C (3) > We have the basic technologies Stable specifications for the basics since 2004: RDF, OWL Work is being done to properly incorporate rules We have a standard for query since 2008: SPARQL We have some additional technologies to access/create RDF data: GRDDL, RDFa, POWDER, … Some fundamental vocabularies became pervasive (FOAF, Dublin Core,…) State of the Semantic Web, Ivan Herman (3) Copyright © 2008, W3C (4) > Lots of Tools (not an exhaustive list!) • Triple Stores • Middleware • RDFStore, AllegroGraph, Tucana • IODT, Open Anzo, DartGrid • RDF Gateway, Mulgara, SPASQL • Ontology Works, Ontoprise • Jena’s SDB, D2R Server, SOR • Profium Semantic Information Router • Virtuoso, Oracle11g • Software AG’s EII, Thetus Publisher, Asio, SDS • Sesame, OWLIM, Tallis Platform • … • … • Semantic Web Browsers • Reasoners • Disco, Tabulator, Zitgist, OpenLink Viewer • Pellet, RacerPro, KAON2, FaCT++ • … • Ontobroker, Ontotext • Development Tools SHER, Oracle 11g, AllegroGraph • • SemanticWorks, Protégé • … • Jena, Redland, RDFLib, RAP • Converters • Sesame, SWI-Prolog • flickurl, TopBraid Composer • TopBraid Composer, DOME • GRDDL, Triplr, jpeg2rdf • … • … • Semantic Wiki and CMS systems • Search Engines • Semantic Media Wiki, Platypus • Falcon, Sindice, Swoogle • Visual knowledge • … • Drupal 7 Inspired by “Enterprise Semantic Web in Practice”, Jeff Pollock, Oracle. See also -
Standardization's All Very Well, but What About the Exabytes of Existing
Standardization’s all very well, but what about the Exabytes of Existing Content and Learner Contributions? Felix Mödritscher 1), Victor Manuel García-Barrios 2) 1) Institute for Information Systems and New Media, Vienna University of Economics and Business Administration, Augasse 2-6, 1090 Vienna, Austria [email protected] 2) Institute for Information Systems and Computer Media, Graz University of Technology, Inffeldgasse 16c, 8010 Graz, Austria [email protected] 1. Problem Definition Standardization in the field of technology-enhanced learning focuses on structuring and aggregating assets to interoperable educational entities, like a course package. However, available standards and specifications in this area do not include an approach for addressing semantics embedded in existing content. This consideration might be useful for user-centered concepts, like learners tagging or commenting existing material, as well as for automated mechanism, like extracting relations or other meta-information automatically from the resources. In the upcoming section we indicate application areas and explain why available standards and specifications do not support these scenarios. Thereafter, we present a XML- based description language for semantics embedded in web-based content, which might be a solution for these use cases. Finally, we summarize and discuss some experiences on in- content semantics from former projects, particularly AdeLE (Adaptive e-Learning with Eye- tracking, http://adele.fh-joanneum.at) and iCamp (http://icamp.eu), and give an outlook on future work. 2. Application Areas and Shortcomings of Standards In 2004 we came in the situation that we had to cope with semantic enrichment of existing learning content, precisely to enable facilitators to tag web-based resources.