In the previous two chapters we have seen first FOL and then a version of it that was slightly changed with respect to notation and number of features in the language (easier, and less, respectively), being the DL family of languages. They haven’t gotten us anywhere close to implementations, however. This is set to change in this chapter, where we will look at ‘implementation versions’ of DLs that have rich tooling support. We will take a look at the computational use of DLs with a so-called serialization to obtain computer-processable versions of an ontology and automated reasoning over it.
- 4.0: Prelude to the Web Ontology Language
- The language that we will use to serialize the ontology is the most widely used ontology language for computational purposes, being the Web Ontology Language OWL. OWL was standardised first in 2004 and a newer version was standardized in 2009, which has fuelled tool development and deployment of ontologies in ontology-driven information systems. OWL looks like yet another a language and notation to learn, but the ones that we will consider (the DL-based ones) have the same underlying principles.
- 4.1: Standardizing an Ontology Language
- This section and the next one are intentionally kept short, as listing language features isn’t the most interesting of content, those lists exist also online in the standard1, and are not meant to be memorised but to be consulted as the need arises. This section and the next one, instead, focus on the gist of it and provide some contextual information.
- 4.2: OWL 2
- Work towards a standardisation of an OWL 2 took shape after the OWL Experiences and Directions workshop in 2007 and a final draft was ready by late 2008. On October 27 2009 it became the official OWL 2 W3C recommendation. What does OWL 2 consists of—new and improved!—and what does it fix with respect to the OWL standard of 2004? Let’s consider the answers to these questions in the remainder of this section.
- 4.3: OWL in Context
- OWL was designed for the World Wide Web, and has a place there, which is outlined in the next subsection. A different notion of ‘positioning’ OWL is with respect to the language features, or: options to link OWL to more expressive languages, which is described afterward.