Another issue is that some concepts and individuals may not naturally belong in a single unique location in the ontology, being multiply classified by experts and/or auto- mated methods. While most ontology languages permit multiple inheritance, rampant multiple classification erodes the classificatory utility of the ontology and increases the computational complexity of population (see next section). We have attempted to finesse this issue by limiting concepts to a single appearance per subdiscipline while adding “semantic crosslinks” to the ontology. These crosslinks capture the relatedness of ideas deemed mutually relevant by feedback or automated methods yet which have been manually classified by experts in distant areas of the ontology.