12.5 Reusing Existing Ontologies 293
Definitions of nouns are usually expressed by comparing them with more
general nouns. While verbs can also be defined this way, it is not as useful
as it is for nouns. In practice, most verbs are defined in terms of the corre-
sponding noun, which is defined in the usual way. This fails to address the
role that a verb plays, which is to express relationships between concepts.
Consider the following definition of “inject:”
give an injection to; "We injected
the glucose into the patient’s vein"
The definition begins by defining the verb in terms of the corresponding
noun. The usage example that follows is the more interesting part of the
definition. It suggests that “inject” relates some agent (e.g., some medical
practitioner) with a substance (in this case, glucose). One can also specify
the location where the injection occurs (e.g., the patient’s vein).
Here are some usage examples for the medical chart ontology:
George is a patient.
George is in the infectious disease ward.
George was admitted on 2 September 2004.
Dr. Lenz noted that George was experiencing nausea.
George’s temperature 38.9 degrees C.
Nausea is classified using code S00034.
Summary
- Ontologies are based on domain knowledge.
- The following are the main sources of domain knowledge for ontology
development:
- Statement of purpose of the ontology
- Glossaries and dictionaries
- Usage examples
12.5 Reusing Existing Ontologies
If an ontology already exists for some of the terminology in your domain,
then it is sometimes better to use the existing ontology than to construct it
