MACHINE LEARNING - INTRODUCTION
DEFINITION:
Machine
Learning is a set of methods that can automatically detect patterns in data and then use the uncovered patterns
to predict future data or to perform other kinds of decision making under uncertainty (such as planning
how to collect more data).
LEARNING PROBLEM:
A computer program is said
to learn from experience E with respect to some
class of tasks T and performance measure P, if its
performance at tasks in T,
as measured by P, improves with experience E.
Example: a computer program
that learns to play checkers P in this case is measured by its ability to win
T in this case is playing checkers games
E in this case is obtained by playing games against itself
In general,
to have a well-defined learning problem we must
identify these three features:
1.
The class of tasks (T)
2.
The measure of performance to be improved
(P)
3.
The source of experience (E)
Checkers learning
problem:
·
Task T – playing
checkers
·
Performance measure
P – percent of games
won against opponents
· Training experience E – playing
practice games against
itself
Handwriting recognition learning
problem:
·
Task T – recognizing and classifying
handwritten words within
images
· Performance measure P – percentage of words correctly classified
· Training Experience E – a database of handwritten words with given classifications
Robot driving learning problem:
·
Task T – driving on
public four lane highways using vision
sensors
· Performance measure P – average distance travelled before an
error (as judged by human
overseer)
· Training experience E – a sequence of images and steering commands
recorded while observing a human
driver
E-mail classification:
·
Task T: Categorize email messages as spam or legitimate.
· Performance P: Percentage of email messages correctly classified.
· Training Experience E: Database of emails, some with human-given labels
