CSC 110 – Fluency in Information Technology Chess Dr. Curry Guinn

Today’s Class A Look Ahead Computer Chess Lab

What’s Next? November 21 Fri Natural Language Processing November 24 Mon Futuristic Stuff November 26 Wed No Class November 28 Fri No Class December 1 Mon Review December 3 Wed Exam #2 December 10 Wed Final Exam Due

Computer Chess Chess playing machines have been around longer than computers The Turk

The Turk 1769 Complicated gear works Could beat very, very good players It was a hoax. The Turk: The Life and Times of the Famous Eighteenth-Century Chess-Playing Machine

Computer Chess Programs first developed in 1958 In 1997, Gary Kasparov lost a six game match to Deep Blue (3.5-2.5). The primary algorithm used is called MINIMAX. How does it work?

Minimax relies on an Evaluation function The Evaluation function rates how good a particular configuration is In chess, the evaluation of a board position might include: Number and type of pieces remaining on the board How mobile are your pieces? Do you control the center of the board? Is the king in a safe position?

Minimax Algorithm See what moves are possible for you Then for each of those moves, see what your opponent can do Then for each of those moves, see what you can do … Then see what your opponent can do … And so on. When you stop looking at possible moves, evaluate those final board positions. Determine which sequence of moves will guarantee you the highest score. You will always choose the move that results in a higher score; Your opponent will always choose the move that results in a lower score

MAX A B C MIN D E F G MAX 1 1 -3 4 1 2 -3 4 -5 1 -7 2 -3 -8 = terminal position = agent = opponent

Problems with Minimax How far can you search in the tree? In chess, between 25-40 moves possible on average. So at each level of the tree, you could have 25 branches. After 1 move, 25 possible boards. After 2 moves, 252 = 625 After 3 moves, 253 = 15, 625

Depth of Minimax After 4 moves, 254 = 390, 625 … After 10 moves, 2510 = 95, 367, 431, 640, 625 Searching to depth = 40, at one game per microsecond it would take 1090 years to make its first move Age of universe = 1010

Depth of Minimax (Deep Blue) 480 specialty chess chips Parallel computing: 30 workstations Searches 12 plies (turns) 25^12 = 59 quadrillion Extends promising lines as must as 40 plies PLUS opening database PLUS end-game algorithms

So Is It Intelligent?

Games where MiniMax doesn’t work too well Go Branching factor of 200 Games can go on for 250+ moves Very difficult to evaluate board positions This is the HOT game to study in AI Card games Too much variability due to chance

Lab: Part 1 Here’s another art program. It’s pretty good. http://www.kurzweilcyberart.com/

Lab: Play Chinook Chinook is the best checkers player in the world Try it: http://games.cs.ualberta.ca/~chinook/cgi-bin/player.cgi?nodemo

Some great AI demos and movies A page with some of the best computer game players: http://www.cs.ualberta.ca/%7Egames/

Wrap-up Why is Natural Language Processing so hard? Read this paper: http://people.uncw.edu/guinnc/papers/ittsec_nlp.97.pdf