KR Ontology

Figure 4.1: Hierarchy of Top-Level categories in KR Ontology

The KR Ontology has been developed by John F. Sowa in sowa1. A graphical representation of the top-level categories and their connection can be seen in figure 4.1. Sowa established seven primitive categories: Independent, Relative, Mediating; Physical and Abstract; Continuant and Occurrent. The twelve categories in the center of figure 4.1 are each generated by three of the basic categories, one of each group.

Additionally, there are two general types, $\top$ and $\bot$. $\top$ is the super-type of all types, and all individuals are instances of $\top$. $\bot$ is a subtype of all types and no individual is an instance of $\bot$.

Abstract is information without any carrying entity. It exists outside of time and space. No matter the physical encoding of information, whether paper or bits or a verbal report, the same entity, the same information exists in all of them, and it is an abstract. Physical is an entity that exists in space and time. Independent is an entity that exists independent of any relationships to other entities. Therefore the characteristic feature is some kind of firstness. Relative is an entity that has to be in relationship to some other entity to exist. Mediating is an entity, that brings other entities into relationship. An example is ``John is kissing Mary.'' Then there exists an individual kiss, bringing John and Mary into relationship. Mediating is therefore characterized by some kind of thirdness. A Continuant or Endurant is an entity that exists over some period of time. It exists in space, but has no temporal parts of its own. At any point of time where the entity exists, it exists as a whole. A Occurrent has temporal parts, that are called stages. It may exists on different places during different stages. A lifetime may be considered an occurrent.

We do not want to describe all of KR Ontology, so let us now consider the relevant concepts needed to gain an insight on situations in the KR Ontology.

An Actuality is an independent physical entity. The term is due to Whitehead, and is the same as Aristotle's ousia or Descartes' res vera. Instances are objects and processes.