ontological engineering – representing abstract concepts (e.g. actions, time, physical objects, and beliefs
upper ontology – a general framework of concepts

have to handle exceptions and uncertainty

2 major characteristics of general-purpose ontologies that distinguish them from special-purpose ontologies:

§  a general purpose ontology can be applicable in any special purpose domain (with the addition of domain-specific axioms)

§  different areas of knowledge must be unified because reasoning and problem solving involves several areas simultaneously (e.g. circuitry requires knowledge domains of time, electrical connectivity, and physical layout. The sentences describing time should be capable of being combined with sentences describing physical layout and electrical connectivity)