Query Answering with Description Logic Ontologies

Meghyn Bienvenu and Magdalena Ortiz

  • Area: LoCo
  • Level: A
  • Week: 2
  • Time: 17:00 – 18:30
  • Room: C2.01

Abstract

Recent years have seen an increasing interest in ontology-mediated query answering, in which the semantic knowledge provided by an ontology is exploited when querying data. Adding an ontology has several advantages (e.g. simplifying query formulation, integrating data from different sources, providing more complete answers to queries), but it also makes the query answering task more difficult. In this course, we give a introduction to ontology-mediated query answering using description logic (DL) ontologies. Our focus is on DLs for which query answering scales polynomially in the size of the data, as these are best suited for applications requiring large amounts of data. We  describe the challenges that arise when evaluating different natural types of queries in the presence of such ontologies, and we present algorithmic solutions based upon two key concepts: query rewriting and saturation. We conclude the course with an overview of recent results and active areas of ongoing research.

Although there are no formal prerequisites, some familiarity with description logics, knowledge representation and reasoning, and/or databases would be helpful. Students who are not already familiar with description logics are strongly encouraged to attend the foundational course “Description Logics: a Nice Family of Logics” offered during Week 1.

Slides

Handout

Unit 1: Introduction

Unit 2: Instance Queries

Unit 3: Conjunctive Queries

Unit 4: Navigational Queries

Unit 5: Queries with Negation and Other Forms of Recursion

Unit 6: Research Topics in OMQA

Unit 7: Ontology-Based Data Access with Ontop

Additional References