RDF scheme

RDF schema (RDFS)
File extension :	no
Developed by:	World Wide Web Consortium  (W3C)
Current version:	1.1 (as of February 25, 2014)
Type:	Extension of the RDF vocabulary
Extended by:	RDF
Standard (s) :	RDF schema 1.1 (W3C Recommendations)
Website :	RDF scheme 1.1

The Resource Description Framework Schema ( RDFS ) is like RDF is a W3C recommendation. Just as XML requires the definition of a special document type in a specific application, e.g. B. as a document type definition (DTD), the RDF model only defines a syntax for the common data exchange. A common vocabulary such as Dublin Core is required to interpret statements formulated in RDF . Such a vocabulary is also called an ontology if it also contains rules for the correct use of the resources defined in it .

RDF schema (RDFS) provides a vocabulary that can be used to model a specific application domain. In addition, the resources occurring in the domain , their properties and relationships with one another can be represented by RDFS. So you can formalize simple ontologies with RDFS . RDFS is based on the idea of ​​a set theoretical class model. It is important that classes and properties are modeled separately from one another. The class concept makes it possible to define a formal description of the semantics of the RDF elements used.

In addition to RDFS, there are a number of other ontology description languages ​​such as F-Logic , DAML + OIL . The Web Ontology Language (OWL), the official successor to DAML + OIL , aims to eliminate the shortcomings of RDFS. OWL is partly based on description logic and has been enriched by set- theoretical constructs.

RDF schema terms

RDF itself provides the element as the only term for typingtype . In addition, however, in order to generate a taxonomy , for example , additional terms (class, property, derivation, ...) are required. With the following terms it is possible to define a formal vocabulary for a certain area of knowledge , i.e. to create a primitive ontology :

• Classes
  • Class: The class concept. Defines an abstract object and is used in conjunction with rdf:typeto create instances.
  • Resource: Each entity in an RDF model is an instance of this particular class.
  • Property: The base class for properties. Is a subclass of Resource.
  • Literal: Class for literal values , i.e. strings etc.
• properties
  • subClassOf: A transitive property used to define inheritance hierarchies of classes.
  • subPropertyOf: A transitive property used to define inheritance hierarchies for properties.
  • domain: Specifies the data type (class) of the subject of a property. For example, the class Auto could be specified as domainthe property hasKFZKennzeichen . It follows that all subjects with the property hasKFZKennzeichen are of the type Auto (from hatKFZKennzeichen domain Auto and a thing hatKFZKennzeichen L-XYZ-00000 follows a thing isA car ). The reverse conclusion that only classes of the specified domain can appear as subjects of a property is incorrect.
  • range: Specifies the data type of the object of a property. For example, it can be stated that the value of a property hasColor is a color (from hasColor range color and a ball has color blue follows blue is one color ). The reverse conclusion that only classes of the range can appear as an object of a property is incorrect.

Formal definition of RDF using the RDF scheme

On the website of the World Wide Web Consortium there is a formal definition of the RDF model in RDF schema. The following resources are defined therein:

• Classes
  • Statement: Triple of a statement
  • Property: A property that can be used as a predicate of a statement.
  • Bag: Disordered amount of resources
  • Seq: Ordered set of resources
  • Alt: Amount of alternative resources
• properties
  • subject: Assigns a resource as a subject to a statement
  • predicate: Assigns a property to a statement as a predicate
  • object: Assigns an object to a statement
  • type: Identifies the class of a resource
  • value: Simple assignment of a property

literature

• Pascal Hitzler, Markus Krötzsch, Sebastian Rudolph, York Sure: Semantic Web. Basics . Springer, 2008, ISBN 978-3-540-33993-9

Web links

• W3C RDF Schema Specification

Individual evidence

1. ↑ RDF scheme 1.1. Retrieved October 12, 2018 . 
2. ↑ RDF scheme 1.1. Retrieved October 12, 2018 . 
3. ↑ 22-rdf-syntax-ns. World Wide Web Consortium, accessed June 5, 2005 .