Ontologies and Taxonomies

The mapping of information aiming to facilitate information discovery is addressed by the introduction of ontologies and taxonomies. These are descriptions of an information space in a manner that is widely accepted by the stakeholders in a thematic area. For example, ontologies exist for the description of cultural information. Ontologies also exist for the description of scientific information and data.

The word ontology comes from the Greek words “on” and “logos”, the latter meaning reason. Ontologies date back to the 17th century BC and the discipline of philosophy in ancient Greece. The word taxonomy refers to the Greek word “taxis”, which means order, division, and law.

• Conceptualization’ refers to an abstract model of phenomena in the world by having identified the relevant concepts of those phenomena.
• Explicit’ means that the type of concepts used, and the constraints on their use are explicitly defined.
• Formal’ refers to the fact that the ontology should be machine readable.
• 'Shared' reflects that ontology should capture consensual knowledge accepted by the communities

An ontology is more than a taxonomy: Ontologies include richer relationships between terms. It is these rich relationships that enable the expression of domain-specific knowledge. This is a key distinction.

In the modern world, Gruber worked with ontologies. According to him, “an ontology is a formal, explicit specification of a shared conceptualization”, where:

Ontologies and taxonomies are used for information modelling, that is, they are modelling the real world, or somebody’s perception of the real world.

Conceptual models can be created representing a wide range of objects ranging from in-formation to processes. The goal of conceptual is to narrow the gap between the real world and the computer based representation of it. A good example of varying perceptions of the real world is displayed in the figure below, which shows how a cat is perceived by its owner and by a veterinarian. Both presented perceptions are correct, however they represent different viewpoints.

The above example leads to an important observation: information must be modelled tak-ing into account the target group that will consumer it as well as the ways through which it will be used