programming-for-dummies

Problem Solving 645
Game-playing
Because teaching a computer how to solve a variety of problems is hard,
computer scientists decided to limit the scope of the problems a computer
might face. By limiting the types of problems a computer might need to
solve, computer scientists hoped to figure out the best ways to teach
computers how to learn.
Solving any problem involves reaching for a goal, so the first test of artificial
intelligence revolved around teaching computers how to play games. Some
games, such as tic-tac-toe, have a small set of possible solutions that can be
identified in advance. Because there’s only a small number of possible solutions
to the problem of playing tic-tac-toe, it’s easy to write algorithms that
specifically tell the computer what to do in any given situation.
The game of chess is an example of a hard problem because the possible
number of valid moves is far greater than any human programmer can write
into a program. Instead, human programmers have to give the computer
guidelines for solving a problem. These guidelines are heuristics.
A heuristic is nothing more than a general set of rules to follow when faced
with similar problems. Telling a child to look both ways before crossing the
street is an example of a heuristic. Telling a child to look left and then look
right before crossing the corner of 5th Street and Broadway is an example of
a specific direction, which is absolutely useless for solving any problem
except that one.
Book VII
Chapter 4
To teach a computer to play chess, programmers typically use a tree data
structure (see Book III, Chapter 5) that the computer creates before making a
move. The tree represents all possible moves, so the human programmer
simply writes algorithms for telling the computer how to solve each problem
by gathering information about that problem. Because games have distinct
rules, teaching a computer to play a game also taught computer scientists
the best way to teach a computer to solve any type of problem.
Artificial
Intelligence
Of course, the problem with this theory is that teaching a computer to play
chess created a great computer that can only play chess. Game-playing
taught computer scientists only how to make computers play better games
but not be able to solve problems outside a fixed set of rules.
Not surprisingly, the one area that has benefited from game-playing research
has been using artificial intelligence techniques to create better computer
opponents in video games. The next time you play your favorite video game
and the computer seems particularly clever, you can thank all the research
in AI for making smarter video games.