In the past few years, ontologies have emerged as a valuable tool for representing the semantic context of a domain; ontologies provide the required formalism for computers to perform automated reasoning and the high level semantics for humans to work with. A number of tools have emerged that facilitate the creation, maintenance, usage and visualization of ontologies, such as Protégé, KAON, etc. Insofar, however, ontology tools are targeted to maintaining ontology snapshots, i.e. the most recent version of ontologies; past values of properties or relationships are not maintained, neither the period that the values/relationships were in effect can be stored. Some tools encompass ontology versions, which though cannot be effectively used for maintaining entity evolution since, generally, the number of changes in properties and/or relationships is too high, resulting in an excessive and unmanageable number of version.
This work is an extension of the Protégé tool to accommodate the modeling and presentation of entity history, i.e. past values of properties and/relationships; each such value is timestamped with the period that it was (or will be) valid in the real world. To this end, the presented extension provides:
- integrated support for data types expressing time quantities – more specifically dates (individual points in time) and periods (anchored segments of the time axis).
- data types for storing histories of properties of different types (strings, integers, floats, booleans and instances [i.e. relationships]).
The extension can be used in contexts that the modeling of entities’ history is important, such as historical archives, museums, etc.
Note: The wt-Protégé project is an extension of t-Protégé, providing additionally support for weighted data.