Using Ontology-Based Data Access to Enable Context Recognition in the Presence of Incomplete Information

Abstract

Classical OBDA regards however only a single moment [7], which means that information about time cannot be used for reasoning and is thus lost.In the doctoral dissertation [17], we therefore investigate temporal query languages that allow to access temporal data through classical ontologies. In particular, we study the computational complexity of temporal query answering regarding ontologies written in lightweight description logics, such as DL-Lite [2,11], which are known to allow for efficient reasoning in the atemporal setting and are successfully applied in practice.We also present a so-called rewritability result for ontology-based temporal query answering, which suggests ways for implementation. In this article, we present an overview of our results. They may guide the choice of a query language for temporal OBDA in data-intensive applications that require fast processing, such as context recognition. Ontology-Based Temporal Query AnsweringConsider the following example context: "a user watches a video, but, after a while, works with a text editor that hides the video window". In such a situation, the operating system could optimize resource consumption by decreasing quality parameters of the video. For recognizing the context, it has to be encoded into a temporal query and answered over data about different points in time (i.e., different system states). Ontologies can augment this approach by providing an abstract, user-friendly interface to the data and by stating general domain knowledge, which can be taken into account during query answering.The setting we focus on is depicted in Fig. 1. The temporal query addresses a temporal knowledge base (TKB) that consists of an ontology and fact bases. We specifically

Temporal Conjunctive Query Answering in the Extended DL-Lite Family

“…These results have been extended to SHOQ-LTL [59]. Rigid names lead to NEXPTIME-completeness even in EL-LTL and DL-Lite-LTL [23,75].…”

“…The logics ALC-LTL [18], SHOQ-LTL [59], EL-LTL [23], and DL-Lite-LTL [10,75] allow for combining DL axioms (CIs and facts) via LTL operators, but no temporal concepts. The setting where the concept inclusions are required to hold globally represents a simplified variant of the TCQ answering scenario, since assertions can be seen as simple CQs (without variables) and the fact bases are empty.…”