Download
1 / 35
350 likes | 368 Views
G5BAIM Artificial Intelligence Methods. History. Graham Kendall. Predictions. “Within 10 years a computer will be a chess champion” Herbert Simon, 1958 Conversion from Russian to English, when presented with “The spirit is willing but the flesh is weak” produced
E N D
G5BAIMArtificial Intelligence Methods History Graham Kendall
Predictions • “Within 10 years a computer will be a chess champion” • Herbert Simon, 1958 • Conversion from Russian to English, when presented with • “The spirit is willing but the flesh is weak” produced • “The vodka is good but the meat is rotten” • National Research Council, 1957
The Travelling Salesman Problem • A salesperson has to visit a number of cities • (S)He can start at any city and must finish at that same city • The salesperson must visit each city only once • The number of possible routes is (n!)/2
Combinatorial Explosion A 10 city TSP has 181,000 possible solutions A 20 city TSP has 10,000,000,000,000,000 possible solutions A 50 City TSP has 100,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000 possible solutions There are 1,000,000,000,000,000,000,000 litres of water on the planet Mchalewicz, Z, Evolutionary Algorithms for Constrained Optimization Problems, CEC 2000 (Tutorial)
Combinatorial Explosion - Towers of Hanoi • How many moves does it take to move four rings? • You might like to try writing a towers of hanoi program (and you may well have to in one of your courses!)
Combinatorial Explosion - Towers of Hanoi • If you are interested in an algorithm here is a very simple one • Assume the pegs are arranged in a circle • 1. Do the following until 1.2 cannot be done • 1.1 Move the smallest ring to the peg residing next to it, in clockwise order • 1.2 Make the only legal move that does not involve the smallest ring • 2. Stop • P. Buneman and L.Levy (1980). The Towers of Hanoi Problem, Information Processing Letters, 10, 243-4
Combinatorial Explosion - Towers of Hanoi • A time analysis of the problem shows that the lower bound for the number of moves is 2N-1 • Since N appears as the exponent we have an exponential function
Combinatorial Explosion - Towers of Hanoi • The original problem was stated that a group of tibetan monks had to move 64 gold rings which were placed on diamond pegs. • When they finished this task the world would end. • Assume they could move one ring every second (or more realistically every five seconds). • How long till the end of the world?
Combinatorial Explosion - Towers of Hanoi • > 500,000 years!!!!! Or 3 Trillion years • Using a computer we could do many more moves than one second so go and try implementing the 64 rings towers of hanoi problem. • If you are still alive at the end, try 1,000 rings!!!!
Combinatorial Explosion - Optimization • Optimize f(x1, x2,…, x100) • where f is complex and xi is 0 or 1 • The size of the search space is 2100 1030 • An exhaustive search is not an option • At 1000 evaluations per second • Start the algorithm at the time the universe was created • As of now we would have considered 1% of all possible solutions
Microseconds since Big Bang Microseconds in a Day Combinatorial Explosion
10 20 50 100 200 1/10,000 second 1/2500 second 1/400 second 1/100 second 1/25 second N2 1/10 second 3.2 seconds 5.2 minutes 2.8 hours 3.7 days N5 1 second 35.7 years > 400 trillion centuries 45 digit no. of centuries 1/1000 second 2N 185 digit no. of centuries 445 digit no. of centuries 2.8 hours 3.3 trillion years 70 digit no. of centuries NN Combinatorial Explosion Running on a computer capable of 1 million instructions/second Ref : Harel, D. 2000. Computer Ltd. : What they really can’t do, Oxford University Press
Definition of AI Systems that think like humans Systems that think rationally Systems that act like humans Systems that act rationally
Definition of AI Systems that think like humans Systems that think rationally Systems that act like humans Systems that act rationally Top Left = Cognitive Science
Definition of AI Systems that think like humans Systems that think rationally Systems that act like humans Systems that act rationally Top Left = Cognitive Science Bottom Left = The Turing Test
Definition of AI Systems that think like humans Systems that think rationally Systems that act like humans Systems that act rationally Top Left = Cognitive Science Bottom Left = The Turing Test Top Right = Logical Approach
Definition of AI Systems that think like humans Systems that think rationally Systems that act like humans Systems that act rationally Top Left = Cognitive Science Bottom Left = The Turing Test Top Right = Logical Approach Bottom Right = Acting to achieve one’s goals
Definition of AI Systems that think like humans Systems that think rationally Systems that act like humans Systems that act rationally Top = Thought Processes and Reasoning
Definition of AI Systems that think like humans Systems that think rationally Systems that act like humans Systems that act rationally Top = Thought Processes and Reasoning Bottom = Behaviour
Definition of AI Systems that think like humans Systems that think rationally Systems that act like humans Systems that act rationally Top = Thought Processes and Reasoning Bottom = Behaviour Left = Measure success against ourselves
Definition of AI Systems that think like humans Systems that think rationally Systems that act like humans Systems that act rationally Top = Thought Processes and Reasoning Bottom = Behaviour Left = Measure success against ourselves Right = Measure against rationality
Definition of AI Systems that think like humans Systems that think rationally Systems that act like humans Systems that act rationally
Not Examinable - but in notes • Turing Test • Chinese Room • Physical Symbol System Hypothesis • ELIZA • MYCIN • Forward/Backward Chaining • Means End Analysis
G5BAIMArtificial Intelligence Methods End of History Graham Kendall
