owlObjectProperty

An owlObjectProperty is a type of property in the Web Ontology Language (OWL) used to relate two individuals. It represents a binary relationship between objects, as opposed to data properties that connect an individual to a literal value. In OWL terminology, the built-in type is owl:ObjectProperty, and the term owlObjectProperty is a common informal reference to this concept. Object properties are declared with an IRI and can be used in class expressions and property assertions.

Object properties can have various characteristics and relationships. They may be inverseOf another object property, allowing reasoning about the relation in the opposite direction. They can be transitive (if a relates to b and b relates to c, then a relates to c), symmetric (if a relates to b, then b relates to a), reflexive or irreflexive, and functional or inverse-functional (restricting the number of related objects). They can also be subproperties of more general properties and have domain and range constraints describing expected subjects and objects.

OWL supports restrictions on object properties within class expressions, including someValuesFrom (existential), allValuesFrom (universal), and cardinality constraints (min, max, exact). For example, a class Person may have someValuesFrom hasParent to a Person, meaning every person has at least one related Person via hasParent. Inverse properties let the reasoner infer the converse relationship.

Usage notes: Object properties are central to OWL knowledge graphs. They are used in explicit triples and can be inferred by reasoners. They differ from data properties, which link individuals to literals. Common built-in object properties include owl:sameAs and owl:inverseOf, and properties can have subproperties and various characteristics as needed.