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A pragmatic glossary of Semantic Technology terms

Terminology

LOD

Linked Open Data

An initiative to open up your data, publish them according to semantic web standards and link them to other sources.

This leads to a web of data, as compared to the current web of documents.

The semantic web is actually a virtual database, no longer a virtual library...

LOD2

An FP7-project to develop the infrastructure that is needed to build LOD, or the data web. Kicked-off in September 2010, for 4 years.

Check the status of the project at lod2.eu

OWL

Web Ontology Language

A broader set of classes and properties for more expressive modeling. Subsets of OWL are specified to keep it performant, like OWL-DL for Description Logic purposes.

R2RML

RDB to RDF Mapping Language*

The standard to convert data in Relational Databases into RDF. As such RDB’s are the largest source of RDF data!

* a standard in progress...

RDF

Resource Description Framework

RDF is the standard data model in semantic technology. It tells us to work with triples. We divide the world in small pieces of information:

something has a relationship with another thing

Sophie has father John

(Sophie, hasFather, John)

a triple!

By the way, every part of the triple gets a URI to refer to it. The relationship as well!

In this way, everything gets connected...

RDFa

RDF in attributes*

The standard to turn HTML into RDF. As such HTML is the 2nd biggest source of RDF data!

RDFa is the bridge between the web of documents and the web of data.

* a standard in progress...

RDFS

RDFSchema

A standard semantic modeling language. Very restricted features, it allows creating classes and subclasses, properties and subproperties.

SKOS

Simple Knowledge Organization System

SKOS is a vocabulary to describe Knowledge Organization Systems like thesauri or taxonomies. Like any vocabulary it is created using terms in a specific language, OWL in this case.

SPARQL

Simple Protocol and RDF Query Language

SPARQL is the standard to query RDF data. In fact SPARQL is to RDF Data Stores what SQL is for Relational Databases.

SWRL, RIF

Semantic Web Rule Language, Rule Interchange Format

Rule languages built upon semantic standards. Such languages can be usefull to express rules that could not be expressed in your model using strictly OWL.

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URI

Uniform Resource Identifier

URI’s are used to identify the smallest pieces of information that we want to refer to.

[ URI’s were created in the early 90’s as a way to express names and addresses of objects on the world wide web. On the semantic web we recycle this standard].

ontology

“theory about the nature of being”

Literally ‘ontology’ means the study of being. It is a common term in filosophy and psychology since centuries.

In a semantic technology context ‘ontology’ refers to the model typically used to capture the meaning of data. It is a representation of the knowledge domain you’re working in. Can be expressed in SKOS, OWL or RDFS.