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School of Information Engineering Knowledge Engineering 2012–13 Solutions of Test 5 – 6th February 2014 1 5 pt Explain the relationship between a DL like SROIQ(D) and FOL. Then describe the advantages and disadvantages of implementing a KB using a DL like SROIQ(D) instead of FOL. Lecture Notes, in particular Chapters 2 and 4. 2 15 pt Requirements: 1. A person may be a friend of a person; and if a person is a friend of a person, then the latter is a friend of the former. 2. A person is a friend of every friend of his or her friends. 3. Everybody is a friend of him-­‐ or herself. 4. A person is a friend of every sibling of his or her friends. (Note: a sibling is a sister or a brother.) 5. For every person there is at least one person who is not a friend of the former. 6. Ann is a friend of Bob, Bob is a friend of Charles, but Charles is not a friend of Diana. DL queries: 7. Bob is not a friend of Diana. 8. List all friends of Ann. 9. It is possible that a person has no friends. 10. Every person who has siblings also has friends. 1.1 friendOf: Person ⎯→ Person 1.2 friendOf − ⊑̇ friendOf or Sym(friendOf) 2. friendOf ∘ friendOf ⊑̇ friendOf or Tra(friendOf) 3. If it were possible without violating nonstructural constraints, the specification would be: Person ⊑ ∃friendOf.Self However this axiom is not acceptable in OWL 2 because friendOf is composite by axiom 2. No useful approximation is possible. 4.1 hasSibling: Person ⎯→ Person 4.2 friendOf ∘ hasSibling ⊑̇ friendOf 5. This is not trivial, because in OWL 2 there is no general complement constructor for properties. To specify analogous requirements, the following pattern may be used: notFriendOf: Person ⎯→ Person DisPro(friendOf,notFriendOf) Person ⊑ ∃notFriendOf − However, in this case DisPro is not allowed because…