Discerning and Characterising Types of Competency Questions for Ontologies

TL;DR

This paper introduces a theoretical model classifying five main types of Competency Questions (CQs) for ontologies, aiming to improve their formulation and effectiveness in ontology development, supported by a new annotated CQ repository.

Contribution

It presents the first comprehensive model categorizing CQs into five types and provides an annotated CQ repository to aid ontology development and research.

Findings

Five main CQ types identified: Scoping, Validating, Foundational, Relationship, Metaproperty.

Annotated repository ROCQS includes 438 CQs for research and practical use.

Model improves clarity and effectiveness of CQs in ontology tasks.

Abstract

Competency Questions (CQs) are widely used in ontology development by guiding, among others, the scoping and validation stages. However, very limited guidance exists for formulating CQs and assessing whether they are good CQs, leading to issues such as ambiguity and unusable formulations. To solve this, one requires insight into the nature of CQs for ontologies and their constituent parts, as well as which ones are not. We aim to contribute to such theoretical foundations in this paper, which is informed by analysing questions, their uses, and the myriad of ontology development tasks. This resulted in a first Model for Competency Questions, which comprises five main types of CQs, each with a different purpose: Scoping (SCQ), Validating (VCQ), Foundational (FCQ), Relationship (RCQ), and Metaproperty (MpCQ) questions. This model enhances the clarity of CQs and therewith aims to improve on the effectiveness of CQs in ontology development, thanks to their respective identifiable distinct constituent elements. We illustrate and evaluate them with a user story and demonstrate where which type can be used in ontology development tasks. To foster use and research, we created an annotated repository of 438 CQs, the Repository of Ontology Competency QuestionS (ROCQS), incorporating an existing CQ dataset and new CQs and CQ templates, which further demonstrate distinctions among types of CQs.