Monotonic vs, non -monotonic Rules(3) The solution with rules r1 and r2 works in case we have complete information about the situation The new kind of rule system will find application in cases where the available information is incomplete e R2 is a nonmonotonic rule 11 Chapter 5 A Semantic Web primer
11 Chapter 5 A Semantic Web Primer Monotonic vs. Non-monotonic Rules (3) ⚫ The solution with rules R1 and R2 works in case we have complete information about the situation ⚫ The new kind of rule system will find application in cases where the available information is incomplete ⚫ R2’ is a nonmonotonic rule
Exchange of Rules Exchange of rules across different applications E.g., an online store advertises its pricing, refund, and privacy policies, expressed using rules The Semantic Web approach is to express the knowledge in a machine-accessible way using one of the Web languages we have already discussed We show how rules can be expressed in XML-like languages ( rule markup languages) 12 Chapter 5 A Semantic Web primer
12 Chapter 5 A Semantic Web Primer Exchange of Rules ⚫ Exchange of rules across different applications – E.g., an online store advertises its pricing, refund, and privacy policies, expressed using rules ⚫ The Semantic Web approach is to express the knowledge in a machine-accessible way using one of the Web languages we have already discussed ⚫ We show how rules can be expressed in XML-like languages (“rule markup languages”)
Lecture Outline Introduction 2. Monotonic Rules: EXample 3. Monotonic Rules: Syntax Semantics 4. Nonmonotonic Rules: Syntax 5. Nonmonotonic Rules: Example 6. A dTd For Monotonic rules 7. Adtd For nonmonotonic rules 13 Chapter 5 A Semantic Web primer
13 Chapter 5 A Semantic Web Primer Lecture Outline 1. Introduction 2. Monotonic Rules: Example 3. Monotonic Rules: Syntax & Semantics 4. Nonmonotonic Rules: Syntax 5. Nonmonotonic Rules: Example 6. A DTD For Monotonic Rules 7. A DTD For Nonmonotonic Rules
Family Relations e facts in a database about relations mother(X,Y), x is the mother ofY father(X,Y), X is the father ofY male(x), x is male female(X), X is female Inferred relation parent: a parent is either a father or a mother mother(X, Y> parent(XY) father(X,Y)-> parent(X,Y) 14 Chapter 5 A Semantic Web primer
14 Chapter 5 A Semantic Web Primer Family Relations ⚫ Facts in a database about relations: – mother(X,Y), X is the mother of Y – father(X,Y), X is the father of Y – male(X), X is male – female(X), X is female ⚫ Inferred relation parent: A parent is either a father or a mother mother(X,Y) → parent(X,Y) father(X,Y) → parent(X,Y)
Inferred relations male(X), parent(P,X), parent(PY), notsame(X,Y> brother(X,) female(X), parent(P,X), parent(PY), notsame(X,Y) → sister(x,Y brother(X, P),parent(P,Y>uncle(X,Y mother(X, P), parent(P,Y> grandmother(XY) parent(X,Y)->ancestor(XY) ancestor(X, P), parent(PY)->ancestor(XY) 15 Chapter 5 A Semantic Web primer
15 Chapter 5 A Semantic Web Primer Inferred Relations ⚫ male(X), parent(P,X), parent(P,Y), notSame(X,Y) → brother(X,Y) ⚫ female(X), parent(P,X), parent(P,Y), notSame(X,Y) → sister(X,Y) ⚫ brother(X,P), parent(P,Y) → uncle(X,Y) ⚫ mother(X,P), parent(P,Y) → grandmother(X,Y) ⚫ parent(X,Y) → ancestor(X,Y) ⚫ ancestor(X,P), parent(P,Y) → ancestor(X,Y)