1. Pertemuan 2 PROBLEMS, PROBLEM SPACES, AND SEARCH
Matakuliah : T0264/Inteligensia Semu
Tahun : Juli 2006
Versi : 2/1
Pertemuan 2 PROBLEMS, PROBLEM SPACES, AND SEARCH

2. << TIK-99 >> << TIK-99>>
Learning Outcomes
Pada akhir pertemuan ini, diharapkan mahasiswa
akan mampu :
<< TIK-99 >>
<< TIK-99>>

3. Outline Materi
Materi 1
Materi 2
Materi 3
Materi 4
Materi 5

4. Building a Problem-Solving Program
To build a system to solve a particular problem, needed four things :
Define the problem precisely
Analyze the problem
Represent the task knowledge
Choose and apply representation and reasoning technique

5. 2.1 Defining the Problem as a State Space Search
One Legal Chess Move

6. Another Way to Describe Chess Moves
White pawn at
Square(file e, rank 2)
AND
Square(file e, rank 3)
is empty
Square(file e, rank 4)
Move pawn from TO

7. A Water Jug Problem
You are given two jugs, a 4-galon one and a 3-galon one. Neither has any measuring marker on it. There is pump that can be used to fill the jugs with water. How can you get exactly 2 gallons of water into the 4-galon jug ?

8. A Water Jug Problem

9. Production Rules for the Water Jug Problem

10. Production Rules for the Water Jug Problem

11. One Solution to the Water Jug Problem
Gallon in the 4-gallon Jug
Gallon in the 3-gallon Jug
Rule Applied 3 2 9 4 7
5 or 12
9 or 11

12. To provide a formal description of problem, do the following :
To Specify a Problem
To provide a formal description of
problem, do the following :
Define the state space that contain all possible configurations of the relevan objects
Specify one or more the initial states
Specify one or more the goal states
Specify a set of rules that describe the actions (operator) available

13. Contoh Kasus
Seorang Petani akan menyeberangkan seekor Kambing, seekor Harimau dan Sayuran dengan sebuah rakit keseberang sungai. Rakit hanya muat petani dengan satu penumpang lainya. Jika ditinggal petani maka kambing dimakan harimau dan sayuran dimakan kambing.
Buatlah representasi ruang keadaan agar keempat obyek sampai diseberang sungai masih lengkap.

14. A set of rules Knowledge / database A control strategy A rule applier
2.2 Production Systems
A set of rules
Knowledge / database
A control strategy
A rule applier

15. Termasuk dalam Blind Search
Search Techniques
Termasuk dalam Blind Search
Breadth First Search : semua node dikunjungi sehingga jika ada solusi pasti diketemukan atau tidak terjebak jalan buntu. Tetapi membutuhkan memori besar dan waktu pencarian relatif lama.
Dept First Search : node dikunjungi dari ranting paling kiri. Jika ada solusi bisa diketemukan lebih cepat, membutuhkan memori kecil dan waktu pencarian lebih singkat. Tetapi bisa terjebak dalam jalan buntu.

16. Algorithm : Breadth – First Search Set Node-List to the initial state
2.2.1 Control Strategies
Algorithm : Breadth – First Search
Set Node-List to the initial state
Until a goal is found or Node-List is empty do :
Remove the first element of Node-List and call it E.If Node-List was empty,quit
For each rule match againtst E do :
Apply the rule to generate a new state
If the nem state is a goal, quit and return it
Else,add the new state to the end of Node-List

17. Two level of a Breadth-First Search Tree

18. Algorithm : Dept-First Search
1.If the initial state is a goal state, quit and return succes
2.Otherwise,do the following until succes or failure is signaled :
Generate a successors,E,of the initial state.If there are no more successors,signal failure
Call Depth-First Search with E as the initial state
If succes is returned,signal success. Otherwise continue in this loop

19. A Depth-First Search Tree

20. Some Simple Heuristic Functions
2.2.2 Heuristic Search
Some Simple Heuristic Functions
Chess
The material advantage of our side over the opponent
Travelling Salesman
The sum of the distances so for
Tic-Tac-Toe
1 for each row in which we could win and in which we already have one piece plus 2 for each such row in which we have two pieces

21. Heuristic Search
Heuristic Search is a technique that improves the efficiency of a search process, possibly by sacrificing claims of completeness. Heuristic like tour guides.
Some heuristics help to guide a search process without sacrificing any claims to completeness that the process might previously have had.

22. 2.3 Problem Characteristics
Is the problem decomposable ?
Can solution steps be ignored or undone ?
Is the problem’s universe predictable?
Is a good solution absolute or relative ?
Is the desired solution a state of the world or a path to a state ?
Is a large amount of knowledge absolutely required to solve the problem, or is it important only to constrain the search ?
Must problem-solving be interactive?

23. Decomposable Problem

24. 2.4 Production System Characteristics
A monotonic production system is a production system in which the application of rule never prevents the later application of another rule that could also have been applied at the time the first rule was selected.
A nonmonotonic production system is one in which this is not true.
A partially commutative production system is production system with the property that if the application of a particular sequence of rules transform state x into state y, then any permutation of those rules that is allowable also transform state x into state y.
A commutative productions system is production system that is both monotonic and partially commutative.

25. Production System Characteristics
The four Categories of Production Systems
Monotonic
Nonmonotonic
Partially commutative
Theorem proving
Robot navigation
Not Partially commutative
Chemical syntesis
Bridge

26. 2.5 Design of Search Programs
Some important issues that arise in all of them :
The direction in which to conduct the search (forward vs backward reasoning)
How to select applicable rules (matching)
How to represent each node of the search process (the knowledge representation problem and frame problem)

27. Design of Search Programs
A Search Graph for the Water Jug Problem
(4,0)
(0,0)
(0,3)
(1,3)
(4,3)
(3,0)

28. 2.6 Additional Problems
The Missionarries and Cannibals
The Tower of Hanoi
The Monkey and Bananas
Cryptarithmetic

29. << CLOSING>>
End of Pertemuan 2
Good luck