ABSTRACT
Recall the wumpus introduced in Section 2.3.2. The knowledge deduced by this wumpus consisted of simple facts about the environment such as whether there is a breeze in a particular square. Similarly, the knowledge deduced by the systems discussed in Section 2.3.1 consisted of simple facts such as the type of a plant or the bag location of a particular item. In these simply applications, there was little need to concern ourselves with an abstract representation of the knowledge. However, in more complex domains, this is not case. Knowledge representation is the discipline that represents knowledge in a manner that facilitates drawing inference from the knowledge. In philosophy, ontology is the study of the nature of existence and what is real. It concerns what entities can be said to exist, how they can be categorized, and the relationships among the categories. In artificial intelligence, an ontology is a representation of knowledge as a set of concepts and relationships that exist among those concepts.
