This book is my attempt at providing the first textbook for an introduction in ontology engineering. Indeed, there are books about ontology engineering, but they either promote one specific ontology or methodology only, are handbooks, or are conference proceedings. There have been collaborative initiatives that aimed for a generic introduction, yet they have not made it to the writing stage. Problems to overcome with such an endeavour—aside from the difficult task of finding time to write it—are, mainly, to answer the questions of 1) which topics should an introductory textbook on ontology engineering cover? and 2) how comprehensive should an introduction be? The answer to the first question is different for the different audiences, in particular with respect to emphases of one topic or another and the order of things. The intended audience for this textbook are people at the level of advanced undergraduate and early postgraduate studies in computer science. This entails, for instance, that I assume the reader will know what UML class diagrams and databases are. As computing degrees seem to have a tendency to have become less theoretical, a solid background in logic, reasoning, and computational complexity is not expected, so a gentle introduction (or recap, as it may be) of the core concepts is provided. There are no lengthy philosophical debates in any of the chapters, but philosophical aspects are presented and discussed mainly only insofar as they are known to affect the engineering side. There still will be sections of interest for philosophers and domain experts, but they may prefer to work through the chapters in a different order (see ‘how to use the book’).
As to how comprehensive an introduction to ontology engineering should be, there is no good answer. At least for this first version, the aim is for a semester-long course, where each chapter can be covered in a week and does not requite too much reading of core material, with the core material being the contents of the chapter. For an introductory course at undergraduate level, the citations in the text may be ignored, but it serves to read 1-3 scientific papers per chapter for more detail, especially if this book is used in a postgraduate course. This makes also sense in the light that ontology engineering is still an active field of research—hence, some basics may change still—and it allows for flexibility in a course programme so as to emphasise one topic more than another, as the lecturer may prefer. The in-text references also may help students to start reading scientific papers when they are working on their assignments, as a place to start the consultation of the literature.
I hope I have succeeded in striking a good balance on topics & depth in the first two blocks of the textbook. Suggestions for improvement are welcome. (Knowing that ontologists can be a quite critical group, perhaps I should add to that: antes de criticarme, intenta superarme, i.e., before you criticise me, try to do a better job at writing an ontology engineering textbook than me.)
The contents of the textbook was written by gradually improving, extending, and further updating material that started with blog posts in 2009 for the European Masters in Computational Logic’s Semantic Web Technologies course I taught at the Free University of Bozen-Bolzano, Italy, in 2009/2010, with the hope of generating and facilitating online discussions. That failed miserably, but the posts were visited often. The blogposts were reworked into short syllabi for the Ontology Engineering courses at the University of Havana and University of Computer Science, Cuba, in 2010 and at the Masters Ontology Winter School 2010 in South Africa, which, in turn, were reworked into the COMP718/720 lecture notes at the University of KwaZulu-Natal and the Ontology Engineering honours course lecture notes at the University of Cape Town, South Africa, of which the latest version was in 2015. All those chapters have been updated for this textbook, new material added, and course-specific data has been removed. I had put a CC BY-NC-SA licence on those 2015 lecture notes, so therefore this book has that Creative Commons licence as well. If you think this sounds problematic: it probably is not; if in doubt, please contact me.
Some contents of this book or associated exercises are adapted from slides or tutorials made by other people, and I would like to thank them for having made that material available for use and reuse. They are (in alphabetic order) Jos de Bruijn, Diego Calvanese, Nicola Guarino, Matthew Horridge, Ian Horrocks, Markus Kr¨otzsch, Tommie Meyer, Mariano Rodr´ıguez-Muro, Frantiˇsek Simanˇc´ık, Umberto Straccia, and David Toman. I also would like to thank the students who were enrolled in any of the aforementioned courses, who provided feedback on the blog posts and lecture notes, and assisted me in fine-tuning where more or less explanations and exercises were deemed useful.
For the rest, it was a lot of hard work, with a few encouragements by some academics who appreciated sections of the lecture notes (thank you!) and some I-ignore-that-advice by others who told me it’s a waste of time because one cannot score brownie points with a textbook anyway. The most enjoyable of all the sessions of updating the contents was the increment from the 2015 lecture notes to the first full draft of the textbook, which was at Consuelo’s casa particular in La Habana in June 2018 and interspersed with a few casino (salsa) lessons to stretch the legs and get-togethers with acquaintances and colleagues.