Giancarlo Guizzardi: Ontology, Semantics, and Explainable AI – Episode 51

Giancarlo Guizzardi
For nearly three decades, Giancarlo Guizzardi has researched and advanced the field of semantics and the practice of ontology and conceptual modeling.
His work on the Unified Foundational Ontology (UFO), the OntoUML pattern language, and AI explainability are just a few of the accomplishments that make him an exemplar of the "full-stack ontologist."
We talked about:
his broad-ranging ontology and other responsibilities work at the University of Twente in the Netherlands
the origins of the term ontology in computer science in 1967
George Mealy's assertion that "every data makes an ontological commitment"
his take on the idea of capital O Ontology, both the conceptual tooling to build ontologies as digital artifacts and the design patterns that guide their creation
how his insight that conceptual modeling is the foundation of any system led to his development of the Unified Foundational Ontology (UFO)
his goal with UFO to give engineers tooling to reuse ontology patterns without having to expose them to the complexity of the underlying ontology itself
the resulting OntoUML pattern language
his belief that ontology engineering should separate conceptual modeling from design and implementation
his take on the difference between verification and validation in ontology design
how conceptual modeling and engineering implementation often end up in the hands of a "full-stack ontologist"
how the ideas in his paper on "Explanation, Semantics, and Ontology" support explainable AI
Giancarlo's bio
Giancarlo Guizzardi is a Full Professor of Computer Science the University of Twente, The Netherlands, where he chairs the Semantics, Cybersecurity & Services (SCS) department. He is also a co-founder and co-director of the NeXAI Competence Cluster in the same university. He has been active for nearly three decades in the areas of Formal and Applied Ontology, Ontology Engineering, Conceptual Modeling, Enterprise Computing and Information Systems Engineering, working with a multidisciplinary approach in Computer Science that aggregates results from Philosophy, Cognitive Science, Logics and Linguistics. He is the main contributor to the upcoming ISO/IEC international standard 21838-5 Unified Foundational Ontology (UFO) and to the OntoUML modeling language. He is an associate editor of several journals including Applied Ontology and Data & Knowledge Engineering, chair of the Steering Committee of the International Conference on Conceptual Modeling (ER), member of the Advisory Board of the International Association for Ontology and its Applications (IAOA), and an ER fellow. Finally, he has extensive technology-transfer experience developing industrial ontologies in sectors such as Health, Cybersecurity, Risk Management, Space, Finance, Energy, Distributed Software Development, Digital Journalism, Complex Media Management, Government.
Connect with Giancarlo online
LinkedIn
GiancarloGuizzardi.com
Resources mentioned in this interview
Another Look at Data, George Mealy's 1967 paper
Explanation, Semantics, and Ontology
Ontology, Ontologies and the “I” of FAIR
Unified Foundational Ontology (UFO)
OntoUML
Video
Here’s the video version of our conversation:
https://youtu.be/JtsC8nQNFF0
Podcast intro transcript
This is the Knowledge Graph Insights podcast, episode number 51. The origins of the practice of ontology in computer science go back almost 60 years, well before the current era of knowledge graph technologies. Since then, ontology researchers like Giancarlo Guizzardi have demonstrated the importance of distinguishing between conceptual modeling and the symbolic language that implements the model. Giancarlo's latest work shows that genuinely explainable AI is impossible without formal ontology and semantics.
Interview transcript
Larry:
Hi everyone. Welcome to episode number 51 of the Knowledge Graph Insights Podcast. I am really delighted today to welcome to the show Giancarlo Guizzardi. Giancarlo is a professor at the University of Twente in the Netherlands. Welcome, Giancarlo. Tell the folks a little bit more about what you're doing these days.
Giancarlo:
Hi, Larry. Thanks for having me. It's a pleasure to be here talking to you. As you said, I'm a professor here in the Netherlands. I'm the head of a group called Semantics, Cybersecurity, and Services. So as the name says, everything we do is grounded on semantics and ontologists. And we call ourselves full-stack ontologists.
Giancarlo:
So we work from very theoretical issues. So sometimes I even publish in philosophy journals, to very practical issues of... So we go from building ontologies in philosophy, ontology in computer science, modeling languages, tools, ecosystems of tools for ontology engineering, and to implementation of ontologies in large-scale settings. So we've been doing this for quite a while in many different domains.
Giancarlo:
The group now is very focused on cybersecurity, on risk management and on social and legal issues. So the service part refers to that. And it's a big group, around 70 people here in the Netherlands.
Larry:
Oh, wow. I didn't realize it was that big. Well, and that scope that you described, and I love that you describe yourself as a full-stack ontologist because there were a number... I just came back from KGC and there were a number of presentations there that they take the semantic layer and divide it into five or six layers of its own, a lot of which aligns with what you just said.
Larry:
But one of the things you talk about, and I think it fits into this, with this deep varied ontology practice spanning a bunch of different domains, different levels from the highbrow ontology stuff to the in-the-weeds data stuff. You argue that capital O, Ontology, like a proper philosophically grounded... Or I don't know exactly what you mean by that, but tell me more about what you mean by capital O, Ontology, and why it's essential for engineering practice?
Giancarlo:
Yes. Ontology, capital O, is basically... So the term refers to three different things, ontology. It refers to, originally in philosophy would refer to a particular theory about a given domain. So what exists in a given domain? So one interpretation is what exists behind a certain description? The ontologist, whatever, a certain description assumes to exist in the world in order for that to be true. So we can see how that connects with data.
Giancarlo:
So there is a quote that I like very much from a guy called Mealy. Mealy is the creator of Mealy Ontology in computer science. He was the PhD supervisor of Peter Chen, the guy that created entity relationship diagrams. So grandfather of conceptual modeling. Mealy writes this paper in 1967 called Another Look at Data, which the first reference of the word ontology in computer science, by the way. So we are talking about ontology in computer science since '67.
Giancarlo:
And Mealy has this nice quote. He says, "data are a theory, a fragment of a theory of the real world." So he's saying every data makes an ontological commitment. This is absolutely inevitable. In fact, any type of representation makes an ontological commitment. So even if you have a kind of Python code that has variables like customer and purchase order and product and so on, you are committing to a given theory of the world of what kinds of things exist with which properties, under which constraints, and so on.
Giancarlo:
And Mealy makes his reference to ontology basically saying, we need to make that explicit, interoperability in a sense. So he's not using these words, but he's saying computer scientists are obsessed with symbols and with symbol manipulation, but we need to look beyond the symbols at what kind of theory of the real world is behind that symbolic structure.
Giancarlo:
So this is a definition of ontology, it's whatever is behind a symbolic structure. In computer science in another area in AI, particularly in the end of the '70s with Pat Hayes and so on, ontology became the structure itself. So the representation of that theory in the background. So these are two interpretations of ontology. Ontology as whatever is in the background, whatever is assumed by a representation, or the representation itself.
Giancarlo:
Well, the representation only justifies its name if it's a representation of the ontology in the background. Otherwise, we could just call this data structure or data model. Ontology, capital O, is a area that allows you to, let's say, flesh out, review, make explicit what is the theory of the real world, which is behind a certain symbolic structure in a systematic way. Or in other words, Ontology, capital O, is an area that will give you instruments, conceptual tools to build ontologies as artifacts. Otherwise, we're going to need to invent these conceptual tools.
Giancarlo:
So typically Ontology, capital O, will deal with the most general aspects of reality, like what are events, what are objects, how objects relate to their parts, how events relate to their parts, what kind of properties can objects have, what kind of relations can connect objects and so on and so forth. What kind of types exist, how types relate to each other forming taxonomic structures, very general theories.
Giancarlo:
So I see these theories as kind of not only conceptual tools, but actually as kind of patterns. So let me give you an example. So imagine if you have a theory of events that says an event is something which happens in space and time, events have parts. So there is a mirror logical structure in events of events. These parts can be related by different types of temporal relations, by causal relations, objects participate in events. So events are kind of dependent entities. In order for them to exist something needs to participate in this event.
Giancarlo:
So you have this theory,...