by John F. Sowa
An excellent article (available online here) I got recommended by on of the reviewer of our "ontology evolution paper".
The paper starts with a simple definition of an ontology (a catalog of things of interest in a domain D expressed in a language L). Afterwards Sowa reviews historical approaches towards ontologies, starting with Aristotle's categories (introducing the term differentia for properties distinguishing different species of the same genus) and Syllogism, which posses some kind of first controlled natural language.
Sowa describes the concept of a conceptual schema linking together databases, applications and user interfaces and presents partial implementations of some aspects of this idea (fourth generation languages like object-orientated programming languages, ...).
After some information regarding trees, lattices and other hierarchies the author motivates ontology sharing and merging. The later one is necessary due to the huge number of specialized standards, terminology and conventions causing problems in aligning terms. Sowa shows how different conceptualizations between vocabulary can complicate aligning and how a word's salience affects term frequency and might lead to differences between the usage of a concept and the usage of terms representing this specific concept.