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Pertemuan 8Representing Knowledge Using Rules

Matakuliah : T0264/Inteligensia Semu Tahun : 2005Versi : 1

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Learning Outcomes

Pada akhir pertemuan ini, diharapkan mahasiswa akan mampu :• << TIK-99 >>• << TIK-99>>

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Outline Materi

• Materi 1• Materi 2• Materi 3• Materi 4• Materi 5

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6.1 Procedural vs Declarative Knowledge

Consider the knowledge base :man(Marcus)man(Caesar)person(Cleopatra)x : man(x) person(x)

Supose we want to answer the questiony : person(y)

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6.1 Procedural vs Declarative Knowledge

We could answer with any one of :y = Marcusy = Caesary = Cleopatra

Now consider an alternative KB :man(Marcus)man(Caesar)x : man(x) person(x)person(Cleopatra)

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6.2 Logic Programming

PROLOG

A PROLOG program is composed of a set of Horn clauses.

A Horn clause is a clause that has at most one positive literal.

Examples : p

p qr s r s

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6.2 Logic Programming

A Declarative and a Procedural Representation

A Representation in Logicx : pet(x) small(x) apartmentpet(x)x : cat(x) dog(x) pet(x)x : poodle(x) dog(x) small(x)poodle(fluffy)

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6.2 Logic Programming

A Representation in PROLOG

apartmentpet(x) : - pet(x), small(x).pet(x) : - cat(x).pet(x) : - dog(x).dog(x) : - poodle(x).small(x) : - poodle(x).poodle(fluffy).

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6.2 Logic Programming

Answering Question in PROLOG

?- apartmentpet(x).

?- cat(fluffy).

?- cat(mittens).

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6.3 Forward vs Backward Reasoning

• Number of start and goal states.

• Branching factor in each direction.

• Need to justify reasoning.

• Triggers for problem solving.

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6.3 Forward vs Backward Reasoning

Sample or the Rules for Solving the 8-Puzzle

Assume the areas of the tray are numbered:

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6.3 Forward vs Backward Reasoning

Square 1 empty and Square 2 contains tile n Square 2 empty and Square 1 contains tile n

Square 1 empty and Square 4 contains tile n Square 4 empty and Square 1 contains tile n

Square 2 empty and Square 1 contains tile n Square 1 empty and Square 2 contains tile n

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6.3 Forward vs Backward Reasoning

An Example :

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6.3 Forward vs Backward Reasoning

A Bad Use of Heuristic Bidirectional Search

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6.4 Matching

Representation Affects Matching

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6.4 Matching

White pawn at Square(file e, rank 2)

ANDSquare(file e, rank 3) move pawn from is empty Square(file e, rank

2)AND to Square(file e, rank 4)

Square(file e, rank 4)is empty

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6.4 Matching

Many-to-Many Matching• The temporal nature of data.• Structural similarity in rules.

mammal(x) feline(x) jaguar(x)carnivorous(x) has-spots(x)mammal(x) feline(x) tiger(x)carnivorous(x) has-stripes(x)

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6.4 Matching

• Persistance of variable binding consistency.son(x,y)

grandparent(x,z)son(y,z)

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6.4 Matching

A Bit of Dialogue with ELIZAPerson: Men are all alike.ELIZA: In what way? Person: They’re always bugging us

about something or other. ELIZA: Can you think of a specific

example? Person: Well, my boyfriend made me

come here. ELIZA: Your boyfriend made you come

here.

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6.4 Matching

Person: He says I’m depressed much of the time.

ELIZA: I am sorry to hear you are depressed.

Person: It’s true. I am unhappy. ELIZA: Do you think coming here will help

you not to be unhappy? Person: I need some help, that much

seems certain. ELIZA: What would it mean to you if you

got some help?

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6.4 Matching

Person: Perhaps I could learn to get along with my mother.

ELIZA: Tell me more about your family.

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6.4 Matching

Some ELIZA - like rules(X me Y) (X you Y)(I remember Z) (Why do remember X just now ?)

(My {family-member} is Y) (Who else in your family is Y)

(X {family-member} Y)(Tell me more about your family)

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6.4 Matching

Conflict Resolution• Preferences based on rules

Rule order Prefer special cases over more general

ones• Preferences based on objects

Prefer some objects to others location in STM

• Preferences based on states

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6.5 Control Knowledge

Syntax for a Control Rule

Under conditions A and B,Rules that do {not} mention X

{ at all, in their left-hand side, in their right-hand side}

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6.5 Control Knowledge

will{ definitely be useless, probably be useless ... probably be especially useful definitely be especially useful}

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