intelligent cs 5 ? hw 11 (1 problem !) m/t sections w/th sections due sunday, 11/14 at midnight due...

Intelligent CS 5 ?

• HW 11 (1 problem !) M/T sections

W/Th sections

due Sunday, 11/14 at midnight

due Monday, 11/15 at midnightRecitation for HW11 -- Friday 11/12, 8:00 am

• 2nd midterm exam -- this Friday, 11/12Take-home, 2.0 hours, closed-book exam. Practice problems are online…

exemption: > 95% HW

Exam will be available this Friday; it’s due Sunday evening by 5:00 pm.

Chess is the Drosophila of artificial intelligence.

The computer that defeated Garry

Kasparov

1997

www.cs.hmc.edu/~dodds/cs5 (top link)

Today’s Lab: M-Z

- Alexander Kronrod

Games: computers vs. humans…

500

1200

2000

2800

Two-player games

early programs ~ 1960’s

• Strategic thinking was considered essential for intelligence• Computer Chess has a long history:

Ranking

beginner

amateur

world ranked

world champion

MacHack (1100) ~ 1967 MIT

Deep Thought ~ 1989 Carnegie Mellon

Slate (2070) ~ 1970’s Northwestern

Deep Blue ~ 1996 IBM

Deep Blue rematch ~ 1997 IBM

500

1200

2000

2800

Computers’ strategy…


• Strategic thinking was considered essential for intelligence• Computer Chess has a long history:

Ranking

beginner

amateur

world ranked

world champion






100’s of moves/sec

10,000’s of moves/sec

100,000,000 moves/sec

200,000,000 moves/sec

how far ahead is this?

500

1200

2000

2800

Games’ Branching Factors


Branching Factor Estimatesfor different two-player games

Tic-tac-toe 4

Connect Four 7

Checkers 10

Othello 30

Chess 40

Go 300

• On average, there are about 40 possible moves that a chess player can make from any board configuration…

Ranking

beginner

amateur

world ranked

world champion






0 Ply

1 Ply

2 Ply

game tree for C4

500

1200

2000

2800




Tic-tac-toe 4

Connect Four 7

Checkers 10

Othello 30

Chess 40

Go 300


Ranking

beginner

amateur

world ranked

world champion






0 Ply

1 Ply

2 Ply

500

1200

2000

2800




Tic-tac-toe 4

Connect Four 7

Checkers 10

Othello 30

Chess 40

Go 300


Ranking

beginner

amateur

world ranked

world champion






“solved” games

computer-dominated

human-dominated

0 Ply

1 Ply

2 Ply

Winning: Details

public boolean winsFor(char ch){ for (int r=0 ; r<this.nrows-3 ; ++r) { for (int c=0 ; c<this.ncols-3 ; ++c) { if (this.data[r+0][c+0] == ch && this.data[r+1][c+1] == ch && this.data[r+2][c+2] == ch && this.data[r+3][c+3] == ch) { return true; } } }

… same idea for vert., horiz., other diag. … return false;}

which diagonals?which board piece?which curly braces?

public boolean winsFor(char ch){ for (int r=0 ; r<this.nRows-3 ; ++r) for (int c=0 ; c<this.nCols-3 ; ++c) if (this.data[r+0][c+0] == ch && this.data[r+1][c+1] == ch && this.data[r+2][c+2] == ch && this.data[r+3][c+3] == ch) return true;

… same idea for vert., horiz., other diag. …

return false;}

Winning: Details (compact version)

Objects hide details!

Class: Board

Object: b

b.winsFor(‘X’) b.addMove(3,‘X’)

‘X’‘O’

capabilities of b

so that important things aren’t lost in the shuffle…

b.removeMove(3)b.isOver()

(the last 3 are new for this week)

0 1 2 3 4 5 6

b.clear()

Objects hide details!

class CS5App{ public static void main(String[] args) { H.pl("Hi! Welcome to Connect 4..."); H.pl("How many rows/columns ? (4-15)"); int R = H.ni(); int C = H.ni(); Board b = new Board(R,C);

char player = 'X';

while (true) { b.print();

int c = H.ni(); // gets next move b.addMove(c,player);

if (b.winsFor(player)) break;

if (player == 'X') player = '0'; else player = 'X'; } // end of while }}

Hw10 Hw11

Where we’re headed…

Player

PlayerplayerForX

Details(data and methods)

PlayerplayerForO


1

2

3

4

Ask what kind of players should play for X and O

Create two objects of class Player with

appropriate inputs

Ask each of these objects to findScores for X and O

and then breakties.

See who wins!

demo…what details are

needed?

charchecker

Picture of a Player object

Player

intlookaheadPlayer

playerForXPlayer(char ch, int lk, int tbk)

inttiebreakType

void printScores(double[] s)

double evaluate(Board b)

double[] plyHuman(Board b)

double[] ply0(Board b)

int breaktie(double[] s)

double[] findScores(Board b)

Imagine if Board weren’t a Class… !

double[] ply1,2,3,4,N(Board b)methods

Player codeprivate char checker;private int lookahead;private int tiebreakType;

public Player(char ch, int la, int tbk) // constructor {

}

public char getChecker() // accessor “getter” method{

}

public char me() // short for getChecker(){

}

public char opp() // returns the opponent’s checker{

}

class Player{

Where we’re headed…

Player

PlayerplayerForX


PlayerplayerForO


1

2

3

4

Ask what kind of players should play for X and O

Create two objects of class Player with

appropriate inputs

Ask each of these objects to findScores for X and O

and then breakties.

See who wins!

demo…what details are

needed?

Hw10class CS5App{ public static void main(String[] args) { H.pl("Hi! Welcome to Connect 4..."); int R = H.ni(); int C = H.ni(); Board b = new Board(R,C);

char player = 'X';

while (true) { b.print();

int uc = H.ni(); // user’s column

b.addMove(uc,player);

if (b.winsFor(player)) break;

if (player == 'X') player = '0'; else player = 'X'; } // end of while }}

Hw11

Choosing a move

1) Find scores at appropriate lookahead…

2) Print the scores.

3) Break ties to determine the next move.

ply0: 0 ply of lookahead

ply1: 1 ply of lookahead

ply2,3,4: 2,3,4 ply of lookahead

plyHuman: ask the user

printScores: prints the scores to each column

breaktie: chooses ONE maximum score

findScoreschooses one of these

methods to run

ply0class Player{ // returns scores with no lookahead // public double[] ply0(Board b) {

charchecker

intlookahead

inttiebreakType

this

b

ply1class Player{ // returns scores with 1ply lookahead // public double[] ply1(Board b) {

charchecker

intlookahead

inttiebreakType

this

b

Which column should have the best score?

• Lookahead 1 move

• Evaluate the results for each column

• Later, we’ll choose the best column to move…

Evaluating a board

Assigns a score to any Board b

Score for X

Score for O

Score for X

Score for O

Score for X

Score for O

100.0 for a win

-1.0 for an invalid move

0.0 for a loss 50.0 for a “tie”

not possible in evaluate

evaluate

class Player{ // returns the appropriate score for b // remember: all of Player’s methods are available public double evaluate(Board b) {

100.0 for a win

-1.0 for an invalid move 0.0 for a loss

50.0 for a “tie”

Improvements? Write tournamentEvaluate for Ex. Cr.!

b

0-ply scores for X:col 0 col 1 col 2 col 3 col 4 col 5 col 6




“Quiz”It is X’s move. .

Compute the score that X would find for each

column for each of these lookaheads:

60 1 2 3 4 5

no moves at all!

X moves

X movesO moves

X movesO movesX moves

class Player{ private int tiebreakType; private int lookahead; private char checker;

public int breaktie(double[] s) { double maxScore = getMax(s); /* assume getMax is already written */

if (this.tiebreakType == 2) /* random tie breaker is tiebreakType == 2 */ {

} }}

Write breaktie to return a randomly chosen best score (max score) from an array of scores named s.

‘X’‘O’new‘X’

b

Looking ahead 1 ply…

(1) For each possible move

(2) Add the column’s move

(3) Evaluate the boards

(4) Choose one of the best

‘X’ to move


Col 6

Col 5

Col 4Col 3Col 2

Col 1

Col 0

b


‘X’ to move




Col 6

Col 5

Col 4Col 3Col 2

Col 1

Col 0

b




(3) Evaluate the boards‘X’ to move

NONE


Col 6

Col 5

Col 4Col 3Col 2

Col 1

Col 0

b


100.0

50.0

100.0100.0

50.0

100.0



(3) Evaluate the boards ‘X’ to move

NONE-1.0


Col 6

Col 5

Col 4Col 3Col 2

Col 1

Col 0

b


100.0

50.0

100.0100.0

50.0

100.0





‘X’ to move

NONE-1.0

ply1public double[] ply1(Board b){

Two-player games have been a key focus of AI as long as computers have been around…

Strategic thinking = intelligence?

Humans and computers have different relative strengths in these games:



computers

good at looking ahead in the game to find

winning combinations of moves


this week…



humanscomputers

good at evaulating the strength of a board for a player

good at looking ahead in the game to find

winning combinations of moves


this week… (extra credit)

How humans play games…

- experts could reconstruct these perfectly - novice players did far worse…

An experiment (by deGroot) was performed in which chess positions were shown to novice and expert players…

How humans play games…

- experts could reconstruct these perfectly - novice players did far worse…

Random chess positions (not legal ones) were then shown to the two groups

- experts and novices did just as badly at reconstructing them!

An experiment (by deGroot) was performed in which chess positions were shown to novice and expert players…

Looking further ahead …

0 ply:

2 ply: 3 ply:

random (but legal) choice of move !

(1) player will win

(2) player will avoid losing

(3) player will set up a win by forcing the

opponent to avoid losing

1 ply:X’s move X’s move X’s move

ply2public double[] ply2(Board b){

depends on ply1 !

•Extra Credit: the plyN method !

Lab this week

You’ll need to write (and use)

Last Names

• Problem 1: A Connect Four Player…

• Extra Credit: tournamentEvaluate & a C4 round-robin

2, 4, 6, and 8-ply lookahead for O will all produce different scores!

Player(char ch, int lk, int tbk)char getChecker()

char me() char opp()

void printScores()

double evaluate(Board b)double[] plyHuman(Board b)double[] ply0(Board b)int breaktie(double[] s)

int go(Board b)

(and the others listed on the HW)

M-Z

double[] findScores(Board b)

http://www.cs.hmc.edu/~ccecka/C4/

O to move

b





“Quiz”It is X’s move. .

Compute the score that X would find for each

column for each of these lookaheads:

60 1 2 3 4 5

no moves at all!

X moves

X movesO moves

X movesO movesX moves

class Player{ private int tiebreakType; private int lookahead; private char checker;

public int breaktie(double[] s) { double maxScore = getMax(s); /* assume getMax is already written */

if (this.tiebreakType == 2) /* random tie breaker is tiebreakType == 2 */ {

} }}

Write breaktie to return a randomly chosen best score (max score) from an array of scores named s.


Col 6

Col 5

Col 4Col 3Col 2

Col 1

Col 0

b


100.0

50.0

-1.0

100.0100.0

50.0

100.0





‘X’ to move

NONE

Winning -- details

public boolean winsFor(char ox){ for (int r=0 ; r<this.nRows-3 ; ++r) { for (int c=0 ; c<this.nCols-3 ; ++c) { if (this.data[r+0][c+0] == ox && this.data[r+1][c+1] == ox && this.data[r+2][c+2] == ox && this.data[r+3][c+3] == ox) { return true; } } }

… same idea for vert., horiz., SW-NE diag. … return false;}

| | | | | | | || | | | | | | || |X| | | | | || |O|X|O| | | || |O|X|X| |O|O||X|O|O|X|X|O|X|--------------- 0 1 2 3 4 5 6.

finds this diagonal:

complete HW10PR2 solutions at http://www.cs.hmc.edu/courses/2002/fall/cs5/week_10/sols.html

static

static methods belong to a class, not an object

H.pl(“I’m a static method”); // lots

double av = averageArray(stocks); // HW 7

int syl = numSyllables(word); // HW 6

double d = Math.sqrt(343.0);

If the static method is in another class, the class name is needed!

opp() and ?:

class Player{ private char checker; // data member

public char opp() // returns opponent’s checker {

}

? : is shorthand for if … else …, but only for deciding between

valuesif else

addMove

Class: Board

Object: b

b.addMove(3,‘X’)

‘X’‘O’

changes b by adding checker ‘X’ into row 3

new‘X’

b before

b after

Adding a move without changing b !

b before

b after

Board nextb = b.newAddMove(3,‘X’);

a new Board with the move added

intelligent cs 5 ? hw 11 (1 problem !) m/t sections w/th sections due sunday, 11/14 at midnight due...

Documents

s northwestern deep

ibm deep blue rematch

mit deep thought

s of movessec

chess player

ply slide

s branching factor

world champion machack