---
title: "Temporal Query Answering in the Description Logic EL"
authors:
  - "Stefan Borgwardt"
  - "Veronika Thost"
doi: ""
url: "https://ijcai.org/proceedings/2015/399"
pdf: "https://ijcai.org/proceedings/2015/0399.pdf"
venue: "Proceedings of the Twenty-Fourth International Joint Conference on Artificial Intelligence"
year: 2015
pages: "2819-2824"
track: "Special Track on Knowledge Representation and Reasoning"
keywords:
---

# Temporal Query Answering in the Description Logic EL

Stefan Borgwardt, Veronika Thost

*Proceedings of the Twenty-Fourth International Joint Conference on Artificial Intelligence*, pages 2819-2824.

## Abstract

Context-aware systems use data collected at runtime to recognize certain predefined situations and trigger adaptations. This can be implemented using ontology-based data access (OBDA), which augments classical query answering in databases by adopting the open-world assumption and including domain knowledge provided by an ontology. We investigate temporalized OBDA w.r.t. ontologies formulated in EL, a description logic that allows for efficient reasoning and is successfully used in practice. We consider a recently proposed temporalized query language that combines conjunctive queries with the operators of propositional linear temporal logic (LTL), and study both data and combined complexity of query entailment in this setting. We also analyze the satisfiability problem in the similar formalism EL-LTL.