OWL Punning: Make Sure Your Ontology Isn't a Joke

In the world of the Semantic Web, a single identifier (IRI) is usually meant to denote only one thing. But what happens when you use the same IRI for two completely different kinds of entities—like an owl:Class and an owl:Individual? That's an OWL pun, and it's where the logical world of OWL DL (Description Logics) clashes with the flexible world of OWL Full.

We'll define the linguistic pun (starting with a terrible post office joke), then tackle the technical pun. We'll explore exactly why these meta-level conflicts break OWL DL reasoners like HermiT and Elk, and what the true cost is—you're forfeiting the guarantees of decidability.

But don't stress! Punning isn't a victimless crime, but it's not a modeling catastrophe either. We'll wrap up with practical advice on when you should be concerned, how to keep your models consistent, and when you can afford to "pun-t" (sorry!).