CSCI 1302

1
CSCI 1302

• Artificial Intelligence

2
Artificial Intelligence

• The Turing Test
• Image Processing/Analysis
• State Trees
• Heuristics
• Neural Networks
• Genetic Algorithms

3
The Turing Test

• Proposed by Alan Turing in 1950
• If I cant tell its not a human, its human
  enough
• Interrogator respondent

?
4
Image Processing/Analysis
5
Image Processing
6
ImageAnalysisto Objects
7
Generating 3D Models from 2D Images and Shadow
Processing
8
State Trees

• Begin with initial state
• Generate all valid states (given rules)
• Breadth-first traverse resultant tree, repeating
• See sample 8-puzzle from 10.3
• Grow VERY fast
• Even tic-tac-toe!

9
Game - Defined

• Search problem with 4 key elements
• Initial state
• Operators (legal moves)
• Terminal test (when is the game over)
• Utility function (numeric outcome of game)

10
Tic-Tac-Toe

• Initial state empty board
• Operators place your mark in empty location
• Terminal test no empty locations or three
  in-line marks
• Utility function -1, 0, 1
• Others for intermediary steps?

11
Initial State
Symmetric boards





Symmetric boards








12
Tic-Tac-Toe TreeStructure

• How many nodes are theoretically possible in a
  min-max game tree?
• What is the amortized branching factor?
• What is the upper bound on the height of the
  tic-tac-toe min-max tree?
• What is the total number of end states (leaf
  nodes) for a tic-tac-toe min-max tree?
• Why is tic-tac-toe boring?

13
Min-Max Algorithm

• Zero-sum game
• My gain is my opponents loss
• Max begins
• Min and Max alternate taking turns
• Each makes move to benefit self (adversarial)
• Apply utility function to predictively move
• Max assumes Min will correctly move
• Half move ply (a.k.a. level in tree)

14
Min-Max Visualized
3
M1
M2
M3
3
2
2
M23
M33
M13
M21
M22
M31
M32
M11
M12
8
12
3
6
4
2
2
5
14
15
A Complex Example
- - - - - - - - -
X - - - - - - - -
- - - - X - - - -
- X - - - - - - -
X O - - - - - - -
X - O - - - - - -
X - - - O - - - -
X - - - - O - - -
X - - - - - - - O
O X - - - - - - -
- X - O - - - - -
- X - - O - - - -
- X - - - - O - -
- X - - - - - O -
O - - - X - - - -
- O - - X - - - -
X O X - - - - - -
X O - X - - - - -
X O - - X - - - -
X O - - - X - - -
X O - - - - X - -
X O - - - - - X -
X O - - - - - - X
O X - - X - - - -
O - X - X - - - -
O - - - X X - - -
O - - - X - - - X
X O - - X - - - -
- O - X X - - - -
- O - - X - X - -
- O - - X - - X -
O O - - X - - - X
O - - - X O - - X
O - O - X - - - X
O O X - X - - - X
O O - X X - - - X
O O - - X X - - X
O O - - X - X - X
O O - - X - - X X
O O O - X X - - X
O O - O X X - - X
O O - - X X O - X
O O - - X X - O X
O O O - X - X - X
O O - O X - X - X
O O - - X O X - X
O O - - X - X O X
O O O - X - - X X
O O - O X - - X X
O O - - X O - X X
O O O X X - - - X
O O - X X O - - X
O O - X X - O - X
O O - X X - - O X
O O - - X - O X X
O O X O X X - - X
O O - O X X X - X
O O - O X X - X X
O O X - X X O - X
O O - X X X O - X
O O - - X X O X X
O O X - X X - O X
O O - X X X - O X
O O - - X X X O X
O O - O X - X X X
O O X O X - X - X
O O - O X X X - X
O O - O X - X X X
O O - O X - X X X
O O X O X - - X X
O O - O X X - X X
O O - - X O X X X
O O X - X O - X X
O O - X X O - X X
O O X - X - O X X
O O - X X - O X X
O O - - X X O X X
O O X X X - - O X
O O - X X X - O X
O O - X X - X O X
O O X X X - O - X
O O - X X X O - X
O O - X X - O X X
O O X X X O - - X
O O - X X O X - X
O O - X X O - X X
More Here
O O O O X X X - X
O O - O X X X O X
O O X X X O - O X
O O X X X - O O X
O O O X X - X O X
O O - X X O X O X
O O X X X O O - X
O O X X X - O O X
O O O X X - O X X
O O - X X O O X X
O O X X X O O - X
O O X X X O - O X
O O O X X O X - X
O O O X X O - X X
O O - X X O O X X
O O - X X O X O X
O O O O X X - X X
O O - O X X O X X
O O O - X X O X X
O O - O X X O X X
O O O - X X X O X
O O - O X X X O X
O O X O X O X - X
O O X O X - X O X
O O O O X X X - X
O O - O X X X O X
O O X O X - O X X
O O X O X O - X X
O O O O X X - X X
O O - O X X O X X
O O X O X O - X X
O O X - X O O X X
O O O X X O - X X
O O - X X O O X X
O O X O X - O X X
O O X - X O O X X
O O O X X - O X X
O O - X X O O X X
O O O - X X O X X
O O - O X X O X X
O O X X X O O X X
O O X X X O X O X
O O X O X X X O X
O O X O X X X O X
O O X O X O X X X
O O X O X X X O X
O O X O X X X O X
O O X O X O X X X
O O X O X O X X X
O O X X X O O X X
O O X X X O O X X
O O X X X O O X X
O O X X X O O X X
O O X X X O X O X
O O X X X X O O X
O O X X X O X O X
O O X X X O O X X
O O X X X X O O X
O O X X X O O X X
O O X X X O O X X
O O X X X O X O X
16
Min-Max Functions

• GenerateChildren
• Takes in a state
• Returns a collection of valid states based upon
  Operators
• UtilityFunction
• Takes in a state
• Returns a numeric value associated w/ state
• ChooseMove
• Takes in state ply-depth (or time)
• Depth or Breadth (iterative deepening) traversal
• Returns best move

17
Heuristics

• Often difficult (too costly) to generate actual
  value for state
• Approximate quickly
• Seed with human function
• Opportunity for machine learning

18
Neural Networks

• Collection of processing units (units)
• Model network of neurons
• Input (set of dendrites)
• Output (axon)
• Processing function (synapse chemical makeup)

19
Processing Unit
threshold
1.5
-2
output (0/1)
3
inputs
-1
weights
If unit receives inputs (1,1,0), effective input
is (1-2 13 0-1) 1this is lt threshold
(1.5), so output is 0. If unit receives inputs
(0,1,1), effective input is (0-2 13 1-1)
2this is gt threshold (1.5), so output is 1.
20
Applications

• Pattern matching
• C T character pixel distinction from 10.4
• Associative memory
• Stable vs. nonstable configurations

21
Artificial Neural Network Associative Memory
Example
Start
Step 1
.5
1
1
.5
.5
1
1
1
1
.5
.5
-1
-1
.5
.5
.5
.5
-1
-1
-1
-1
-1
-1.5
1
1
-1
-1
-1
-1.5
-1.5
1
1
1
1
-1
-1
-1
.5
.5
-1
-1
-1
.5
.5
-1
.5
.5
-1
.5
1
1
.5
.5
1
1
1
1
Step 2
Final
.5
.5
1
1
1
1
.5
.5
.5
.5
-1
-1
-1
-1
-1
-1
-1.5
-1.5
1
1
1
1
-1
-1
-1
-1
.5
.5
-1
.5
.5
-1
.5
.5
1
1
1
1
22
Genetic Algorithms

• Simulates micro evolution survival of fittest
• Start with initial strategies
• Run simulation
• Mark beneficial results
• Progress best strategies
• Possible mutations

23
FIN