text: Ontologies are used to capture knowledge about some domain of interest. An ontology describes the 
  concepts in the domain and also the relationships that hold between those concepts. Different ontology 
  languages provide different facilities. The most recent development in standard ontology languages is 
  OWL from the World Wide Web Consortium (W3C). A good primer on the basic concepts of OWL can 
  be found at: https://www.w3.org/TR/owl2-primer/ 
  
  OWL makes it possible to describe concepts in an unambiguous manner based on set theory and logic. 
  Complex concepts can be built up out of simpler concepts. The logical model allows the use of a reasoner 
  which can check whether all of the statements and definitions in the ontology are mutually consistent and 
  can also recognize which concepts fit under which definitions. The reasoner can therefore help to 
  maintain the hierarchy correctly. This is particularly useful when dealing with cases where classes can 
  have more than one parent. The reasoner can also infer additional information. For example, if two 
  properties are inverses only one value needs to be asserted by the user and the inverse value will be 
  automatically inferred by the reasoner. 
  
  3.1 Components of OWL Ontologies 
  An OWL ontology consists of Classes, Properties, and Individuals. OWL ontologies are an 
  implementation of Description Logic (DL) which is a decidable subset of First Order Logic. A class in 
  OWL is a set, a property is a binary relation, and an individual is an element of a set. Other concepts from 
  set theory are also implemented in OWL such as Disjoint sets, the Empty set (owl:Nothing), inverse 