OWL
The Web Ontology Language (OWL) is a semantic web language design to represent rich and complex knowledge about things, a group of things, and relations between things. The current standard is OWL2. It was published in 2009. It is based on RDF.
Its intent is to reduce Complexity and augment data with meta data.
There are three main OWL artifacts:
- Concepts represent a set of classes, entities, or things within a domain, which are used to classify
Instancesor otherConcepts. - Instances are used to refer to the things represented by the
Concept. These may include concrete objects, or abstracts like numbers or words. - Relationships specify how the objects relate to one another.
Object Properties are used to link Instances to other Instances.
Data Properties link Instances to Values. I.e.: The Instance “Petrol” has a “type” Property with the value “Diesel”, and a “Liters” Property for how much.
OWL is implemented on top of RDF, but looks remarkably like a Labeled Property Graph implemented with RDF. The main difference is that OWL has restrictions to the Labels and Relationships that can be used. These Labels and Relationships are defined in the RDF-OWL schema.