Thoughts on types and their relation to human cognition and language. From the open space session at TMRA 2009.

1. Some observations on types TMRA 2009, November 12, Leipzig Lars Marius Garshol, <larsga@bouvet.no>

2. Types in IT Types are extremely fundamental datatypes in programming languages, classes in OOP, entities/packages/clusters/structs/records pre-OOP entity types in ER and EXPRESS, classes in UML, classes in RDF, topic types in Topic Maps, ...

3. Types in language Consider what nouns really are specifically, common nouns Aren’t most of them topic types? car pencil country person computer ...

4. Types in language (2) What characterizes types is that they have instances You can recognize potential types using a simple “language game” for a potential type y, if there is an x such that you can say “x is a y”, y is a type if you cannot, it is not a type Examples Germany is a country ___ is an electromagnetic force

5. Class hierarchies Consider how we talk about concepts in everyday conversations Child: “What is an ozelot?” Grown-up: “It’s an animal.” Child: “Oh. What kind of animal?” Grown-up: “It’s a kind of cat.”

6. Conclusion Types are fundamental in IT because they are fundamental to how we think and speak Likewise class hierarchies