CHRONOS: A Tool for Handling Temporal Ontologies in Protege

Representing information evolving in time in ontologies is a difficult problem to deal with. Temporal relations are in fact ternary (i.e., properties of objects that change in time involve also a temporal value in addition to the object and the subject) and cannot be handled directly by OWL. The standard solution to this problem is to map all temporal relations to a set of binary ones with new (intermediate) classes introduced by the temporal model applied. Nevertheless, ontologies then become complicated and difficult to handle by standard editors such as Protege (e.g., property restrictions of temporal classes might refer to the new classes rather than to the classes on which they were meant to be defined). It also requires that the user be familiar with the peculiarities of the temporal representation. This is exactly the problem this work is dealing with. We introduce CHRONOS, a plug-in for Protege that enables handling of temporal ontologies in Protege the same way static ontologies are handled. It is implemented as a Tab plug-in for Protege and can be downloaded from the Web.