Jarrar.lecture notes.aai.2011s.ontology part1_introduction


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Jarrar.lecture notes.aai.2011s.ontology part1_introduction

  1. 1. Lecture Notes <br />University of Birzeit<br />2nd Semester, 2010<br />Advanced Artificial Intelligence (SCOM7341)<br />Ontology<br />Part 1Introduction<br />Dr. Mustafa Jarrar<br />mjarrar@birzeit.eduwww.jarrar.info<br />University of Birzeit<br />
  2. 2. Reading Material<br />0) Everything in these slides<br />1)Thomas R. Gruber: Toward Principles for the Design of Ontologies Used for Knowledge Sharing http://tomgruber.org/writing/onto-design.pdf<br />2)Nicola Guarino: Formal Ontology and Information Systems <br />http://www.loa-cnr.it/Papers/FOIS98.pdf<br />
  3. 3. Shared meaning (i.e. formal semantics) of bibliographical Terminology<br />Ontology-based Applications<br />(i) Data Integration and Semantic Mediation<br />Semantic Mediator<br />Product ⊑ ValuatedBy.Price<br />Book ⊑ Product ⊓ hasISBN<br />⊓ hasTitle<br />⊓ hasAuthor<br />Bookstore Ontology<br />
  4. 4. Shared meaning (i.e. formal semantics) of bibliographical Terminology<br />Ontology-based Applications<br />(i) Data Integration and Semantic Mediation<br />Semantic Mediator<br />….<br /><owl:Class rdf:ID="Product" /><br /><owl:Class rdf:ID="Book"><br /> <rdfs:subClassOf rdf:resource="#Product" /><br /></owl:Class><br /><owl:Class rdf:ID="Price" /><br /><owl:Class rdf:ID="Value" /><br /><owl:Class rdf:ID="Currency" /><br /><owl:Class rdf:ID="Title" /><br /><owl:Class rdf:ID="ISBN" /><br /><owl:Class rdf:ID="Author" /><br /><owl:ObjectProperty rdf:ID="Valuated-By"><br /><rdfs:domain rdf:resource="#Product" /><br /><rdfs:range rdf:resource="#Price" /><br /></owl:ObjectProperty><br /><owl:DataProperty rdf:ID=" Amounted-To .Value"><br /> <rdfs:domain rdf:resource="#Price" /><br /><rdfs:range rdf:resource="http://www.w3.org/2001/XMLSchema#string"/><br /></owl:ObjectProperty><br /><owl:DataProperty rdf:ID="Measured-In.Currency"><br /> <rdfs:domain rdf:resource="#Price" /><br /><rdfs:range rdf:resource="http://www.w3.org/2001/XMLSchema#string"/><br />…<br />Bookstore Ontology<br />Specification using <br />OWL<br />(Ontology Web Langauge<br />
  5. 5. Ontology-based Applications<br />(ii)The Semantic Web scenario <br />
  6. 6. <br />“The semantic web” mission:<br />syntax to semantic based search,  The next generation of the web. <br />Ontology<br />Buy mobile-phone from Ramallah<br />Ontology-based Applications<br />(ii)The Semantic Web scenario <br />Represents the meanings of thing, in a way that Google can understand. The meaning is embedded inside web pages.<br />1<br />2<br />3<br />4<br />.<br />.<br />.<br />3 billion pages<br />
  7. 7. Ontology-based Applications<br />(iii) Web Information Systems<br />Information System<br />Conceptual Schema<br />DBMS<br />Apps<br />Logical Schema<br />Query processor<br />Data<br /><ul><li>Each Information System is made for one organization.
  8. 8. Why do we need conceptual schemes? for designing Information systems at the conceptual level.</li></li></ul><li>Ontologies/ Semantics<br />(OWL)<br />IS1<br />ISn<br />Conceptual Schema<br />Conceptual Schema<br /> Agreed data schemes<br />(XML, RDF)<br />DBMS<br />DBMS<br />Logical Schema<br />Logical Schema<br />Apps<br />Apps<br />Query processor<br />Query processor<br />Data<br />Data<br />Ontology-based Applications<br />(iii) Web Information Systems<br />New needs:<br />Open data exchange, inter-organizational transactions, global queries…<br />
  9. 9. Example (Customer Complaint Ontology)<br />Central complaining portal <br />See http://www.jarrar.info/publications/mjarrar-CCFORM-chapter.pdf.htm<br />
  10. 10. Example (Customer Complaint Ontology)<br />See http://www.jarrar.info/publications/mjarrar-CCFORM-chapter.pdf.htm<br />
  11. 11. The Need for a Shared Understanding<br />[Martin Hepp]<br />People, organizations, and computers needs to communicate meaningfully.<br />However, due to different needs and background contexts, there can be widely varying viewpoints and assumptions regarding what is essentially the same subject matter; each may have differing, overlapping and or mis-matched concepts.<br />The consequent lack of a shared understanding leads to poor communication within and between people, organizations, and systems.<br />
  12. 12. The meaning of Meaning<br />Concept<br />“Jaguar“<br />البَغْوَر<br /><ul><li>Humans require words (or at least symbols) to communicate efficiently. The mapping of words to things is indirect. We do it by creating concepts that refer to things.
  13. 13. The relation between symbols and things has been described in the form of the meaning triangle:</li></ul>Ogden, C. K. & Richards, I. A. 1923. "The Meaning of Meaning." 8th Ed. New York, Harcourt, Brace & World, Inc <br />[Carole Goble, Nigel Shadbolt, Ontologies and the Grid Tutorial]<br />
  14. 14. The meaning of Meaning<br />Concept<br />“Jaguar“<br />البَغْوَر<br />Concept: a set of rules we have in mind <br />to distinguish similar things in reality. <br />An instance of a concept<br />(الماصدق)<br />
  15. 15. The puzzle of Meaning<br /><ul><li>A Term (/symbol) may refer to different concepts (Animal: Jaguar, Car:Jaguar)
  16. 16. A Concept might not be agreed among all people (i.e., not exactly the same set of rules are agreed by all people)
  17. 17. An instance may belong to different concepts (Person: Mustafa, Lecturer: Mustafa).</li></ul>Dictionaries represent meanings approximately and informally, mixed with lexical aspects.<br />Ontologies specify the meaning formally and precisely.<br />
  18. 18. Levels of Ontological Precision<br />[Guarino]<br />game(x) -> activity(x)<br />athletic game(x) -> game(x)<br />court game(x) ↔ athletic game(x) ∧ ∃y. played_in(x,y) ∧ court(y)<br />tennis(x) -> court game(x)<br />double fault(x) -> fault(x) ∧ ∃y. part_of(x,y) ∧ tennis(y)<br />game<br />NT athletic game<br /> NT court game<br /> RT court<br /> NT tennis<br /> RT double fault<br />Axiomatized Theories<br />Catalog<br />game<br /> athletic game<br /> court game<br /> tennis<br /> outdoor game<br /> field game<br /> football<br />Glossary<br />Thesaurus<br />tennis<br />football<br />game<br />field game<br />court game<br />athletic game<br />outdoor game<br />Taxonomy<br />OO/DB schema<br />Ontological Precision <br />
  19. 19. Standard Vocabularies are not the Solution<br />Contract: A binding agreement between two or more legal persons that is enforceable by law; an <br />invoice can be a contract.<br />Complaint: An expression of grievance or resentment issued by a complainant against a compliant-recipient, <br />describing a problem(s) that needs to be resolved.<br />Legal Person:An entity with legal recognition in accordance with law. It has the legal capacity to represent <br />its own interests in its own name, before a court of law, to obtain rights or obligations for ….<br />• Defining standard vocabularies is difficult and time-consuming<br />• Once defined, standards don’t adapt well<br />• Heterogeneous domains need a broad-coverage vocabulary<br />• People don’t implement standards correctly anyway<br />• Vocabulary definitions are often ambiguous or circular<br />
  20. 20. A Common Alphabet is not Enough…<br /><Book><br /><Title>Orientalism</Title><br /><Author>Edward Said</Author><br /><Price>11</Price> <br /></Book><br /><aaa><br /><bbb>Orientalism</bbb><br /><ccc>Edward Said</ccc><br /><ddd>11</ddd> <br /></aaa><br />“XML is only the first step to ensuring that computers can communicate freely. XML is an alphabet for computers and as everyone who travels in Europe knows, knowing the alphabet doesn’t mean you can speak Italian or French”<br />Business Week, March 18, 2002<br />
  21. 21. The Need for Meaning Mediation<br />“Lack of technologies and products to dynamically mediate discrepancies in business semantics will limit the adoption of advanced Web services for large public communities whose participants have disparate business processes”<br />Gartner Research, February 28, 2002<br />
  22. 22. Human and Machine Communication<br />[Maedche et al., 2002]<br /><ul><li> ...</li></ul>Machine<br />Agent 1<br />Human<br />Agent 2<br />Machine<br />Agent 2<br />Human<br />Agent 1<br />exchange symbol,<br />e.g. via nat. language<br />exchange symbol,<br />e.g. via protocols<br />Ontology Description<br />Symbol<br />‘‘JAGUAR“<br />Formal Semantics<br />Formal<br />models<br />Internal<br />models<br />commit<br />commit<br />Concept<br />Meaning<br />Triangle<br />MA1<br />MA2<br />HA2<br />HA1<br />commit<br />Ontology<br />commit<br />a specific <br />domain, e.g.<br />animals<br />Things<br />