Grounding Geographic Information

Ontologies need to introduce some primitive symbols used for the definition of more complex ones. These primitive symbols have no formal definitions in the ontology, and as ontologies usually are incomplete axiomatizations, the semantics of the primitives remain ambiguous (Guarino 1998). This shifts the problem of semantic interoperability to the problem of how to ground such primitives. Grounding gives meaning to ontological primitives by relating them to qualities outside the symbol system, and thus stopping infinite regress. In analogy to spatial reference systems, we propose to do so by introducing semantic datums (Kuhn and Raubal 2003) that anchor primitives in physical and reproducible observations.