Abstract
All members of the FunDL family of description logics replace roles with partial functions (features) and have a concept constructor, called path functional dependency (PFD), for expressing extensions of functional dependencies, useful in object-relational data sources. In this paper, we consider generalizing PFDs to path description dependencies (PDD), by allowing inverse features in them, which result in paths being set-valued. We show that logical consequence for partial-𝒟LF𝒟I, one of the most expressive dialects of the FunDL family, remains EXPTIME complete for coherent terminologies, when extended with PDDs. As a first application, we consider referring expression types, which are concept descriptions used to identify individuals in query answers. In the new dialect, such a type denotes a set of concept descriptions. As such, one must prove in advance that any interpretation of any member of the set will never have more than one element. We show that this “singularity condition” can be diagnosed as a collection of logical consequence questions wrt a TBox.