Elisa F. Kendall and Deborah L. McGuinness. Ontology Engineering. Morgan and Claypool, 2019. Definition 12.1: A competency question is a (usually application-related) question towards the KG that is formalised in a query language, together with a formal specification of how an acceptable answer may look. Competency questions focus on functional metrics: • coverage/completeness (but cannot check all cases) • correctness • accessibility (using query answering software) They can be used in several situations: • To define the initial scope (requirements) of a new KG project • To formalise data modelling decisions (how should knowledge be encoded to be accessible) • For regression testing (ensure that KG does not break in the future) Competency questions take a content-oriented view (application- and domain-specific), but the approach can be generalised to set up unit testing: • Define a test suite of queries + (constraints on) expected answers • Automatically run queries to detect problems...