To place “ontologies” in its right context, the first two questions one has to ask and answer are:
- What is an ontology?
- What is it good for? (or: what problems does it solve?)
A very short and informal way of clarifying what “an ontology” in computing is, is that it is a text file containing structured knowledge about a particular subject domain, and this file is used as a component of a so-called ‘intelligent’ information system. Fancy marketing talk may speak of some of those ontology-driven information systems as “like a database, on steroids!” and similar. Ontologies have been, and are being, used to solve data integration problems by providing the common, agreed-upon vocabulary which is then used in a way so that the software understands that, say, an entity
Student of a relational database DB1 actually means the same thing as
AdvancedLearners in some application software OO2. Tools can then be developed to link up those two applications and exchange information smoothly thanks to the shared vocabulary. Over time, people figured out other ways to use ontologies and contribute to solving entirely different problems. For instance, a question-answering system that lets the scientist chat with a library chatterbot to more easily find relevant literature (compared to string and keyword matching), automatically find a few theoretically feasible candidate rubber molecules out of very many (compared to painstaking trial-and-error work in the laboratory), and automated discovery of a new enzyme (outperforming the human experts!).
In the next section (Section 1.1), we have a quick peek at what an ontology— the artefact—looks like, and proceed to the more and less pedantic viewpoints of defining what an ontology is (Section 1.2). We will then look at the original motivations why ontologies were taken up in computing & IT and look at a few examples of other uses and what may be considered as some of the success stories (Section 1.3). Lots of new terms are introduced in this chapter that are fleshed out in much more detail in subsequent chapters. Therefore, it is probably useful to revisit this chapter later on—and don’t be put off if it is not all clear immediately and raises many questions now! In fact, it should raise questions, which hopefully will motivate you to want to have them answered, which indeed will be in the subsequent chapters.