Blondie24

Presented by

Adam Duffy and

Josh Hill

Overview

Introduction to new concepts Design of Blondie24 Testing and results Other approaches to checkers Other approaches to evolutionary

computation Why is this important?

Neural Networks

Nodes connected by links– Input nodes– Hidden nodes– Output nodes

Links have weights

Evolutionary Computation

Based on natural selection– Initialize population– Fitness function– Selection– Cross-over– Mutation

Design of Blondie24

Checkers neural network Values for input nodes

– Red – positive– White – negative– Empty – zero

Piece differential

Design of Blondie24

Connections between squares Subsections

Design of Blondie24

Search methods– Minimax– Alpha-beta pruning– Iterative deepening– Quiescent– Hash table of previously evaluated positions

(maximum of 270,000)

Design of Blondie24

Initial population of 30 Each neural network plays 5 games as red

– +1 for a win– 0 for a draw– -2 for a loss

Top 15 kept, lowest 15 eliminated Copy top 15 and mutate the weights

Blondie24: Advantages

Can learn new strategies Doesn’t have human biases

Blondie24: Disadvantages

Long time Doesn’t make use of expert knowledge

Tests

400 MHz Pentium II 840th generation Played games on zone.com 165 games total (84 as red, 81 as white)

Results

zone.com rating: 2045.85 In top 500 of over 120,000 Better than 99.61% of registered players

Chinook

Primary feature - piece count Looks for certain features Over 40,000 opening lines of play Every ending with <= 8 pieces Higher value to positions with more pieces Rated 2,814 at retirement in 1996

Different Evolutionary Approach

Particle Swarm Optimizers (PSO) Each particle is moved closer to

– Global best– Personal best so far

Other applications

Industry, medicine, and defense Pattern recognition Cancer

More information

Blondie 24: Playing at the Edge of AI by David B. Fogel

Learning to play games using a PSO-based competitive learning approach by L. Messeischmidt and A.P. Engelbrecht

The Advantages of Evolutionary Computation by David B. Fogel

Solving the Game of Checkers by Jonathan Schaeffer and Robert Lake