The theoretical research is devoted to the development, the analysis and the axiomatization of general basic ontologies (top-level ontologies) and their integration into a unified system. Such a reference
system of top-level ontologies is the foundation for a formal framework which supports the construction and the representation of generic and domain-specific ontologies.
The ontological investigations are aimed at the choice, the description, and the analysis of ontologically basic categories and basic relations. Several existing systems are investigated and new categorial systems
will be developed, the first of which is the General Formal Ontology (GFO). One aim is the reduction of existing and newly developed top-level ontologies to a minimal number of basic ontologies.
The ontologically basic categories and basic relations which result from the ontological investigations will be formally described by axioms. The result is intended to be an integrated system of formally axiomatized top-level ontologies which will be extended and complemented by further axioms of several relevant areas.
The systems of axioms, which characterize the basic categories and relations will be investigated with respect to meta-logical aspects. These include investigations of problems concerning concistency, completeness and expressive power. The integration of these systems of axioms is based on the investigation and specification of interpretability relations which hold between them.