Open hpi semweb-06-part1

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Open hpi semweb-06-part1

  1. 1. Semantic Web TechnologiesLecture 6: Applications in the Web of Data 01: Ontological Engineering Dr. Harald Sack Hasso Plattner Institute for IT Systems Engineering University of Potsdam Spring 2013 This file is licensed under the Creative Commons Attribution-NonCommercial 3.0 (CC BY-NC 3.0)
  2. 2. 2 Lecture 6: Applications in the Web of Data Open HPI - Course: Semantic Web Technologies Semantic Web Technologies , Dr. Harald Sack, Hasso-Plattner-Institut, Universität Potsdam
  3. 3. 3 01 Ontological Engineering Open HPI - Course: Semantic Web Technologies - Lecture 6: Applications in the Web of Data Vorlesung Semantic Web, Dr. Harald Sack, Hasso-Plattner-Institut, Universität Potsdam
  4. 4. What is an Ontology?4 „A theory of being, which tries to explain the being itself, by developing a system of universal categories and their intrinsic relationships...“ Philosophy Vorlesung Semantic Web, Dr. Harald Sack, Hasso-Plattner-Institut, Universität Potsdam
  5. 5. What is an Ontology?5 "An ontology is an explicit, formal specification of a shared conceptualization.“ Computer Science Vorlesung Semantic Web, Dr. Harald Sack, Hasso-Plattner-Institut, Universität Potsdam
  6. 6. What is an Ontology?6 Top-Level Ontology (Upper Ontology, Foundation Ontology) Domain Ontology Task Ontology Application Ontology Vorlesung Semantic Web, Dr. Harald Sack, Hasso-Plattner-Institut, Universität Potsdam (acc. to Guarino,1998)
  7. 7. The Semantic Gap7 •The Semantic Web is based on the interoperability of metadata •Among heterogeneous metadata there is a Semantic Gap that can be bridged with the help of ontologies •Problem of the Semantic Gap: • different ontologies can be applied to represent identical knowledge. Vorlesung Semantic Web, Dr. Harald Sack, Hasso-Plattner-Institut, Universität Potsdam
  8. 8. The Semantic Gap - A Simple Example •Let‘s model a world:8 World C C B A B A Initial State Final State Modelling 1: Objects Relations block A on(X,Y) block B clear(X) block C holding(X) table T handEmpty hand H Vorlesung Semantic Web, Dr. Harald Sack, Hasso-Plattner-Institut, Universität Potsdam
  9. 9. The Semantic Gap - A Simple Example •Let‘s model a world:8 World C C B A B A Initial State Final State Modelling 1: Modelling 2: Objects Relations Objects Relations block A on(X,Y) block A on(X,Y) block B clear(X) block B clear(X) block C holding(X) block C onTable(X) table T handEmpty holding(X) hand H handEmpty Vorlesung Semantic Web, Dr. Harald Sack, Hasso-Plattner-Institut, Universität Potsdam
  10. 10. Modelling and Ontologies •behind the model there is an ontology C9 Modelling 1: C B Objectx Relations B A A block A on(X,Y) Final State Initial State block B clear(X) block C holding(X) table T handEmpty hand H ⊤ entity relation table block hand binary unary block A on clear handEmpty table T block B hand A holding block C Axiom: on(X,Y) ⋀ on(Y,Z) → above(X,Z) Vorlesung Semantic Web, Dr. Harald Sack, Hasso-Plattner-Institut, Universität Potsdam
  11. 11. Modelling and Ontologies •behind the model there is an ontology C10 B Modelling 2: C A Objects Relations A B Final State block A on(X,Y) Initial State block B clear(X) block C onTable(X) holding(X) handEmpty ⊤ entity relation block binary unary block A on clear handEmpty block B holding block C onTable Vorlesung Semantic Web, Dr. Harald Sack, Hasso-Plattner-Institut, Universität Potsdam
  12. 12. Ontological Engineering •Ontologies enable interoperability among metadata11 •Therefore, we need •Methods for efficient development of ontologies (Ontology Design) •Methods for efficient comparison of ontologies (Ontology Mapping) •Methods for efficient combination of ontologies (Ontology Merging) •There are automated methods to support Ontological Engineering: •Learning new ontologies from a given set of information resources (Ontology Learning) •Populating existing ontologies with individuals from information resources Vorlesung Semantic Web, Dr. Harald Sack, Hasso-Plattner-Institut, Universität Potsdam
  13. 13. 12 02 - Ontology Design Open HPI - Course: Semantic Web Technologies - Lecture 6: Applications in the Web of Data Semantic Web Technologies , Dr. Harald Sack, Hasso-Plattner-Institut, Universität Potsdam

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