This book is written in homage to Nicola Guarino. It is a tribute to his many scientific contributions to the new discipline, applied ontology, he struggled to establish.
Nicola Guarino is widely recognized as one of the pioneers in formal and applied ontology. Renowned – and sometimes even criticized – for his deep interest for the subtlest details of theoretical analysis, all throughout his career he has held the conviction that all science has to be for the benefit of society at large, hence his motto that ontologies are not just for making information systems interoperable, but also – and more importantly – for making people (users of the systems) understand each other. He was among the first to realize that, to capture the intended meaning of the terms used by an information system, applied ontology has necessarily to be an interdisciplinary enterprise.
Nicola's early career developed in the areas of data systems and expert systems in physics and biomedical engineering. The lack of methodologies in expert systems led him to turn to philosophical logic as a source of inspiration, prompting him to attend the meetings of the analytic philosophy group at the University of Padua, and to discover a whole new world. It was the end of the 1980s and in that period the term ‘ontology’ started to be used to indicate a shared vocabulary across a community. Recognizing the potentials of this idea, Nicola began studying philosophical work. Knowing that language remains one of the pivotal elements in knowledge acquisition and representation, he paired it with the study of linguistic analysis. The combination of the two fields proved to be fundamental to shape his research vision, which could be summarized as: ontological analysis is hard, yet unavoidable to address the pervasive need for explicit, meaningful and transparent information systems. In other words, ontology makes sense.
This book is also a praise to Nicola's continuous efforts to build a community around the new discipline. Thanks to these efforts, we have nowadays an international association, a dedicated journal and a flagship conference, which have become a reference to all members of the community.
In 1998 Nicola inaugurated the conference series ‘Formal Ontology in Information Systems’ (FOIS), which marked the beginning of the new research area; twenty years later, FOIS is still the preferred venue for people to meet, and to present and discuss applied ontology issues. Soon he realized that the discipline was mature enough to have dedicated laboratories so, together with his collaborators in Padua, he joined the Institute of Cognitive Sciences and Technologies (ISTC CNR) and founded the Laboratory for Applied Ontology (LOA)
After some years, he considered the need of establishing a journal specifically dedicated to ontological content, marking the distinction of foundational ontology, an approach based on deep and rigorous ontological analysis, from the approaches focused on syntactical and logical concerns, the so-called lightweight ontologies used in the Semantic Web. To this end, in 2005 he and Mark Musen founded the Applied Ontology journal.
What was still needed was a place open to the community for discussion and coordination of activities in applied ontology. This came in 2009, when the International Association for Ontology and its Applications (IAOA)
Nicola has always believed in the importance of having a research network spread at an international level, with nodes exchanging ideas, information and experience on scientific views and applications of ontology. One example is the International Laboratory on Interacting Knowledge Systems (ILIKS), a European joint virtual laboratory connecting the LOA, the IRIT in Toulouse and the University of Trento, that he established in collaboration with Laure Vieu (IRIT CNRS), and that collected research groups with expertise in computer science, engineering, cognitive science, education and economics.
Finally, this book is the result of the enthusiastic answers we, the editors, had from researchers around the world who belong to this community, who have been influenced by and, in turn, influenced the work of Nicola. Many others unfortunately could not comply with the strict schedule set for this book but made themselves available in other ways, e.g. to review the material and to participate in the public event organized for the presentation of the book.
Contributed papers reflect the large variety of research topics that marked Nicola's impact on the applied ontology community. We clustered them according to five general areas addressed by Nicola in his career and that are briefly described below. For each area we provide a few main references and invite the readers to explore the complete bibliography of Nicola's work to fully appreciate his views and interests.
I – What Is an Ontology?
In the nineties, Nicola published a series of papers devoted to develop an accurate analysis of some crucial notions that the community of knowledge engineering, at that time, was starting to refer to. In particular, he reacted to Gruber's definition of ontology – an ontology is “an explicit specification of a conceptualization” – by proposing his own analysis of what an ontology is, grounded on the formal characterization of the notions of conceptualization and ontological commitment, and on the careful distinction between ‘Ontology’ – the philosophical discipline – and ‘ontologies’ – the engineering artifacts. In his view, the term conceptualization has a semantic connotation, denoting an intensional relational structure (given in terms of possible worlds) that reflects a particular conceptual system. ‘Ontologies’ are instead logical theories devoted to capture given conceptualizations (their ontological commitments), i.e., theories whose intended models are intensional relational structures. At the same time, he started to stress the necessity, in the fields of knowledge representation and conceptual modeling, to introduce an ontological level to make explicit the meaning of the assumed primitives and to distinguish different kinds of ontologies according to their level of generality. In particular, he argued for the fundamental role of top-level ontologies – i.e., ontologies that describe very general notions (e.g. identity, parthood, dependence, or causation) or kinds of entities that are involved in the representation of most application domains (e.g., space, time, matter, object, or event) – in both the systematic development of ontologies and the improvement of interoperability and integration of information systems.
– N. Guarino. The ontological level. In R. Casati, B. Smith and G. White, editors, Philosophy and the cognitive sciences, pages 443–456. Hoelder-Pichler-Tempsky, 1994.
– N. Guarino, M. Carrara, and P. Giaretta. Formalizing Ontological Commitment. In Proceedings of the National Conference on Artificial Intelligence (AAAI-94), pages 560–567. Morgan Kaufmann, 1994.
– N. Guarino and P. Giaretta, Ontologies and knowledge bases: towards a terminological clarification. In N. Mars, editor, Towards Very Large Knowledge Bases, pages 25–32. IOS Press, 1995.
– N. Guarino. Formal Ontology, Conceptual Analysis and Knowledge Representation. International Journal of Human and Computer Studies, 43(5–6):625–640, 1995.
– N. Guarino. Formal Ontology in Information Systems. In N. Guarino, editor, Proceedings of the First International Conference on Formal Ontology in Information Systems (FOIS'98), pages 3–15. IOS Press, 1998.
– N. Guarino, D. Oberle, and S. Staab. What Is an ontology?. In S. Staab and R. Studer, editors, Handbook on ontologies, pages 1–17. Springer, 2009.
– N. Guarino. The ontological level: Revisiting 30 years of knowledge representation. In A. T. Borgida, V. Chaudhri, P. Giorgini, and E. Yu, editors, Conceptual modeling: Foundations and applications: Essays in honor of John Mylopoulos, pages 52–67. Springer, 2009.
II – Knowledge Engineering
Beside clarifying the central notions of ontology and conceptualization, Nicola realized the complexity of, and the huge effort required for, the development of well-founded ontological resources. He then started to work on methodologies and tools able to manage the lifecycle of ontologies and to facilitate their use in information systems.
OntoClean was the first analytical methodology to evaluate and validate the ontological adequacy of taxonomies: by characterizing the classes in the taxonomy by means of philosophical notions (like essence, identity, rigidity and unity), it allows to impose some formal constraints on the structure of such taxonomy.
The IST Project WonderWeb
– N. Guarino and C. Welty. A formal ontology of properties. In International Conference on Knowledge Engineering and Knowledge Management, pages 97–112. Springer, 2000.
– N. Guarino and C. Welty. Identity, Unity, and Individuality: Towards a formal toolkit for ontological analysis. In W. Horn, editor, Proceedings of The European Conference on Artificial Intelligence (ECAI'2000), pages 219– 223. IOS Press, 2000.
– C. Welty and N. Guarino. Supporting Ontological Analysis of Taxonomic Relationships. Data and Knowledge Engineering 39(1):51–74, 2001.
– A. Gangemi, N. Guarino, C. Masolo, A. Oltramari, and L. Schneider. Sweetening ontologies with DOLCE. In International Conference on Knowledge Engineering and Knowledge Management, pages 166–181. Springer, 2002.
– C. Masolo, S. Borgo, A. Gangemi, N. Guarino, and A. Oltramari. The WonderWeb library of foundational ontologies and the DOLCE ontology, WonderWeb Deliverable D18 (final), 2003.
– N. Guarino and C. Welty. An Overview of OntoClean. In S. Staab and R. Studer, editors, Handbook on ontologies, pages 151–171. Springer, 2009.
III – Ontologies and Language
Nicola's cognitive approach to ontology led him to systematically refer to existing linguistic analyses of complex semantic phenomena. This was particularly significant for various features of Dolce. For instance, the chosen approach to qualities was influenced by linguistic questions related to B. Partee's analysis of “the room's temperature is ninety and rising”, and perdurant subcategories reflected famous distinctions in verb classes. So a deep relationship between ontology and language generally acknowledged in philosophy of language – although less so in metaphysics – is at the root of Nicola's work.
On the other hand, a significant impact of his methodological work can be found in the reorganization of linguistic resources like WordNet
– N. Guarino. Some ontological principles for designing upper level lexical resources. In A. Rubio, N. Gallardo, R. Castro, and A. Tejada, editors, First International Conference on Language Resources and Evaluation, pages 527–534. European Language Resources Association, 1998.
– N. Guarino, C. Masolo, and G. Vetere. Ontoseek: Content-based access to the web. IEEE Intelligent Systems and their Applications, 14(3):70–80, 1999.
– A. Gangemi, N. Guarino, C. Masolo, and A. Oltramari. Sweetening Word-Net with Dolce. AI magazine, 24(3):13–24, 2003.
– A. Gangemi, N. Guarino, C. Masolo, and A. Oltramari. Interfacing Word-Net with DOLCE: towards OntoWordNet. In Ontology and the Lexicon: A Natural Language Processing Perspective, pages 36–52. 2010.
IV – Ontological Categories and Relationships
Nicola introduced the ontological level as a bridge between the linguistic and cognitive levels, that he called the subjective levels, and the formal and logical ones, that motivate theories whose interpretation remains arbitrary. The ontological level helps to constrain the interpretation of the vocabulary primitives by setting postulates about the meaning of these terms. But how can the ontological level identify these meanings? To answer this question one has to delineate the boundary of the domains to be modeled, that may be at different levels of generality, ranging from top-level to application level. He thus proposed to see applied ontology as the science which “develops theories of the types of entities existing in (people's assumptions about) given domains of reality, and of the relations between these types.”
From a presentation of the Laboratory for Applied Ontology by Nicola Guarino.
From a presentation of the Laboratory for Applied Ontology by Nicola Guarino.
In Nicola's mind, the ontologist should make available a set of distinct theories that characterize types of entities and relations according to the different ontological stand one may adopt. Among these theories, some deal with notions that – although somehow specific – are necessary to talk about things in the world like space, time, change, physical objects, parts, events. In this vein, Nicola wrote some seminal papers in the nineties to study, from the conceptual and formal viewpoint, the relations of parthood and connection (theories known as mereology and mereotopology). In particular, his research focused on the use of these relations in applications and in natural language, and on their capabilities to characterise space, matter and (physical) objects.
Later on, he worked at the construction of a framework to characterize social reality and, in doing this, he and his colleagues proposed a theory of social roles where the ontological nature of these entities is spelled out. More recently, Nicola resumed the investigation of the notion of event and of the connection between the tensed and tenseless views, showing how these can be integrated in the same ontological framework. In the same period, he has also analyzed the interplay between events and relationships, where the latter are seen as truthmakers of relations.
– N. Guarino, Concepts, Attributes and Arbitrary Relations: Some Linguistic and Ontological Criteria for Structuring Knowledge Bases. Data and Knowledge Engineering, 8(2):249–261, 1992.
– A. Artale, E. Franconi, N. Guarino, and L. Pazzi. Part-whole relations in object-centered systems: An overview. Data & Knowledge Engineering, 20(3):347–383, 1996.
– S. Borgo, N. Guarino, and C. Masolo. A pointless theory of space based on strong connection and congruence. In L. Carlucci Aiello and S. Shapiro, editors, KR 96, Principles of Knowledge Representation and Reasoning, pages 220–229. Morgan Kaufmann, 1996.
– C. Masolo, L. Vieu, E. Bottazzi, C. Catenacci, R. Ferrario, A. Gangemi, and N. Guarino. Social roles and their descriptions. In D. Dubois and C. Welty, editors, Proceedings of the 9th Int. Conf. on Principles of Knowledge Representation and Reasoning (KR 2004), pages 267–277. AAAI Press, 2004.
– N. Guarino and G. Guizzardi. “We need to discuss the Relationship”: Revisiting Relationships as Modeling Constructs. In International Conference on Advanced Information Systems Engineering, pages 279–294. Springer, 2015.
– N. Guarino and G. Guizzardi. Relationships and Events: Toward a General Theory of Reification and Truthmaking. In G. Adorni G., S. Cagnoni S., M. Gori, and M. Maratea, editors, Advances in Artificial Intelligence, pages 237–249. Springer, 2016.
– N. Guarino. On the semantics of ongoing and future occurrence identifiers. In H. C. Mayr, G. Guizzardi, H. Ma, and O. Pastor, editors, Conceptual Modelling, Proceedings of the 36th International Conference, ER 2017, pages 477–490. Springer, 2017.
V – Ontologies and Applications
A paramount contribution of Nicola in the field of conceptual modeling and knowledge engineering consisted in providing an ontological foundation of the primitives used in their models, showing the necessity of making explicit the ontological commitments. Such analyses have prompted new perspectives on conceptual modeling languages as UML (Unified Modeling Language) and contributed to the elaboration of OntoUML.
More recently, Nicola began to focus on notions used in social ontology, working in eGovernment applications, in particular in the emerging discipline of service science, where he brought an important conceptual clarification on the different uses of the term ‘service’ in the business and ICT domains, by relying on a foundational analysis of the notions of commitment and activity. The attention to the economic perspective led to a related study of the notions of value and risk and to the modeling of the main principles of tax legislation and the core concepts of personal income taxes.
Starting from the analysis of services, Nicola soon realized that a sound representation of them could not do without an analysis and representation of the organization and social environment in which such services take place. Ontological modeling was then applied to whole socio-technical systems, and the resulting transparency of the organizational procedures and relative responsibilities became a fundamental element of resilience of the systems themselves. The application of such perspective led to a thorough analysis of business process modeling components, which allows to connect the organization and the information domains.
– N. Guarino, G. Guizzardi. In the defense of ontological foundations for conceptual modeling. Scandinavian Journal of Information Systems, 18(1): Article 1, 2006.
– R. Ferrario and N. Guarino. Towards an Ontological Foundation for Services Science. In D. Fensel and P. Traverso, editors, Future Internet – FIS 2008, Lecture Notes in Computer Science 5468, pages 152–169. Springer Verlag, 2009.
– N. Guarino, R. Ferrario, E. Bottazzi, and G. Sartor. Open Ontology-Driven Sociotechnical Systems: Transparency as a Key for Business Resiliency. In M. De Marco, D. Te'eni, V. Albano, and S. Za,editors, Information Systems: Cross-roads for Organization, Management, Accounting and Engineering, pages 535–542, Springer Verlag, 2012.
– I. Distinto, N. Guarino, and C. Masolo. A well-founded ontological framework for modeling personal income tax. In Proceedings of the Fourteenth International Conference on Artificial Intelligence and Law (ICAIL'13), pages 33–42. ACM, 2013.
– G. Guizzardi, N. Guarino, and J.P.A. Almeida. Ontological Considerations About the Representation of Events and Endurants in Business Models. In M. La Rosa, P. Loos, and O. Pastor, editors, Business Process Management. BPM 2016, Lecture Notes in Computer Science 9850, pages 20–36, Springer Verlag, 2016.
– T.P. Sales, F. Baião, G. Guizzardi, J.P.A. Almeida, N. Guarino, and J. Mylopoulos. The Common Ontology of Value and Risk. In J. Trujillo et al., editors, Conceptual Modeling. ER 2018. Lecture Notes in Computer Science 11157, pages 121–135 Springer Verlag, 2018.
As one can see from this list of topics and the contributions in this volume, Nicola's achievements have impacted the work of many researchers around the world. Nicola's role was even more important to some, among whom us, the editors of this book, as it significantly shaped their own careers.
We are sure that in the future Nicola's work and dedication will continue to influence this community as well as many researchers aiming to establish ontologically sound bases for their research areas.
We thank IOS Press, and in particular Maarten Fröhlich, for their continuous support, the contributors and the reviewers of this volume for their help in making this collection a reality.
Trento, January 2019