artificial intelligence (AI)

1. CS 361
Lac 1-2

2. Artificial Intelligence (AI)

3. WHAT IS AI?
AI is the study of how to make
computers make things which at the
moment people do better.

4. DEFINING THE PROBLEM
 Defining the problem as State Space Search
 Initial state
 Goal state
 Rules: Matching ----- forward ----> Action

5. EXAMPLE (1): WATER JUG PROBLEM
 If you have 2 jugs (4 gallon - 3 gallon), how can you get
exactly 2 gallons into the 4 gallon jug?
 The state space for this problem can be described as the
set of ordered pairs of integers (x,y) such that
x = 0, 1,2, 3 or 4 and y = 0,1,2 or 3; x represents the
number of gallons of water in the 4-gallon jug and y
represents the quantity of water in 3-gallon jug
 The start state is (0,0)
The goal state is (2,n)

6. PRODUCTION RULES FOR WATER JUG PROBLEM
No Current state Next State Description
1 (x,y) if x < 4 (4,y) Fill the 4 gallon jug
2 (x,y) if y <3 (x,3) Fill the 3 gallon jug
3 (x,y) if x > 0 (x-d, y) Pour some water out of the 4 gallon jug
4 (x,y) if y > 0 (x, y-d) Pour some water out of the 3-gallon jug
5 (x,y) if x>0 (0, y) Empty the 4 gallon jug
6 (x,y) if y >0 (x,0) Empty the 3 gallon jug on the ground
7 (x,y) if x+y >= 4 and y >0 (4, y-(4-x)) Pour water from the 3 –gallon jug into the 4 –gallon
jug until the 4-gallon jug is full
8 (x, y) if x+y >= 3 and x>0 (x-(3-y), 3) Pour water from the 4-gallon jug into the 3-gallon
jug until the 3-gallon jug is full
9 (x, y) if x+y <=4 and y>0 (x+y, 0) Pour all the water from the 3-gallon jug into the 4-
gallon jug
10 (x, y) if x+y <= 3 and x>0 (0, x+y) Pour all the water from the 4-gallon jug into the 3-
gallon jug

7. TO SOLVE THE WATER JUG PROBLEM
Gallons in the 4-gallon jug Gallons in the 3-gallon jug Rule applied
0 0 2
0 3 9
3 0 2
3 3 7
4 2 5
0 2 9
2 0

8. THE WATER JUGS PROBLEM – SEARCH TREE
0 , 0
4 3
0 , 3 4 , 0
0 , 0 3 , 04 , 3 1 , 3 4 , 30 , 0
0 , 3 4 , 0 0 , 0 4 , 0 0 , 3 3 , 3 0 , 3 4 , 3 1 , 0
3 , 04 , 24 , 30 , 3 0 , 14 , 00 , 0 1 , 3
4 , 03 , 3 4 , 30 , 2 0 , 0 0 , 34 , 1 1 , 0
0 , 34 , 2 0 , 0 2 , 0 2 , 30 , 1 4 , 3 4 , 0

9. PROBLEM SEARCH
 Blind Search
… Blind Search – Breadth First
… Blind Search – Depth First
 Heuristic Search

10. THE WATER JUGS PROBLEM – SEARCH TREE
0 , 0
4 3
0 , 3 4 , 0
0 , 0 3 , 04 , 3 1 , 3 4 , 30 , 0
0 , 3 4 , 0 0 , 0 4 , 0 0 , 3 3 , 3 0 , 3 4 , 3 1 , 0
3 , 04 , 24 , 30 , 3 0 , 14 , 00 , 0 1 , 3
4 , 03 , 3 4 , 30 , 2 0 , 0 0 , 34 , 1 1 , 0
0 , 34 , 2 0 , 0 2 , 0 2 , 30 , 1 4 , 3 4 , 0

11. BLIND SEARCH – BREADTH FIRST
0 , 0
4 3
0 , 3 4 , 0
3 , 04 , 3 1 , 3
3 , 3 1 , 0
4 , 2 0 , 1
0 , 2 4 , 1
2 , 0

12. THE WATER JUGS PROBLEM – SEARCH TREE
0 , 0
4 3
0 , 3 4 , 0
0 , 0 3 , 04 , 3 1 , 3 4 , 30 , 0
0 , 3 4 , 0 0 , 0 4 , 0 0 , 3 3 , 3 0 , 3 4 , 3 1 , 0
3 , 04 , 24 , 30 , 3 0 , 14 , 00 , 0 1 , 3
4 , 03 , 3 4 , 30 , 2 0 , 0 0 , 34 , 1 1 , 0
0 , 34 , 2 0 , 0 2 , 0 2 , 30 , 1 4 , 3 4 , 0

13. BLIND SEARCH – DEPTH FIRST
0 , 0
4 3
0 , 3
3 , 04 , 3
3 , 3
4 , 2
0 , 2
2 , 0

14. EXAMPLE (2): WATER JUG PROBLEM
 You are given three jugs, a 10-gallon one,
7-gallon one, and 3-gallon one.
 Neither have any measuring markers on it.
 There is a pump that can used to fill the jugs
with water.
 Use Breadth First and Depth First search to get
exactly 5-gallons of water into 7-gallon jug.
 The start state is (0,0,0)
The goal state is (n,5,n)

15. EXAMPLE (3): TRAVERSING A MAZE
 The wall follower, the best-known rule for
traversing mazes, is also known as either the
left-hand rule or the right-hand rule.

16. TRAVERSING A MAZE PROBLEM – SEARCH TREE
A
CB D
FE HG I
KJ
NML

17. TRAVERSING A MAZE PROBLEM – BREADTH FIRST
A
B D
I
K
M

18. TRAVERSING A MAZE PROBLEM – SEARCH TREE
A
CB D
FE HG I
KJ
NML

19. TRAVERSING A MAZE PROBLEM – DEPTH FIRST
A
B D
I
K
M

20. EXAMPLE (4): TRAVERSING A MAZE

21. END