What is machine learning?
Machine Learning is the field of study that gives computers
the ability to learn without being explicitly programmed. Samuel's claim to fame was that back in the 1950's, he
wrote a checkers playing program. And the amazing thing about this
checkers playing program, was that Arthur Samuel himself, wasn't a
very good checkers player. But what he did was, he had to program for it
to play 10's of 1000's of games against itself. And by watching what
sorts of board positions tended to lead to wins, and what sort of
board positions tended to lead to losses. The checkers playing
program learns over time what are good board positions and what are
bad board positions. And eventually learn to play checkers better
than Arthur Samuel himself was able to. By doing this the computer
was able to get so much checkers-playing experience that it eventually
became a better checkers player than Arthur Samuel himself.
Tom defines machine learning as follows. He
says, a computer program is said to learn from experience E, with
respect to some task T, and some performance measure P, if
its performance on T as measured by P improves with experience E.
Example: For the checkers
playing example the experience e, will be the experience of having
the program play 10's of 1000's of games against itself. The task t,
will be the task of playing checkers. And the performance measure
p, will be the probability that it wins the next game of checkers
against some new opponent.
Answer: Task is classifying emails as spam or not spam.
