"Det kan æde dig op"

To dig or not to dig.

The DIG Description Logic Interface: DIG/1.1

This document describes a simple API for a general description logic system.

The DIG Description Logic Interface: DIG/1.0

This document describes a simple API for a general description logic system. This forms the first of a number of such specifications. Later versions will introduce more higher-level functionality. The current, Level 0 specification provides basic access to the reasoning capabilities of a DL reasoner.

Kan Extensions of Institutions

Institutions were introduced by Goguen and Burstall 8, 9, 10, 11] to formally capture the notion of logical system. Interpreting institutions as functors, and morphisms and representations of institutions as natural transformations, we give elegant proofs for the completeness of the categories of institutions with morphisms and representations, respectively, show that the duality between morphi...

Computing left Kan extensions

We describe a new extension of the Todd–Coxeter algorithm adapted to computing left Kan extensions. The algorithm is a much simplified version of that introduced by Carmody and Walters (Category Theory, Proceedings of the International Conference Held in Como, Italy, 22–28 July 1990. Springer) in 1991. The simplification allows us to give a straightforward proof of its correctness and terminati...