Introduction to Learning: Machine Learning is the study of how to build computer systems that adapt and improve with experience. It is a subfield of Artificial Intelligence and intersects with cognitive science, information theory, and probability theory, among others.
Classical AI deals mainly with deductive reasoning, learning represents inductive reasoning. Deductive reasoning arrives at answers to queries relating to a particular situation starting from a set of general axioms, whereas inductive reasoning arrives at general axioms from a set of particular instances.
Classical AI often suffers from the knowledge acquisition problem in real life applications where obtaining and updating the knowledge base is costly and prone to errors. Machine learning serves to solve the knowledge acquisition bottleneck by obtaining the result from data by induction.
Machine learning is particularly attractive in several real life problem because of the following reasons:
Recently, learning is widely used in a number of application areas including,
Formally, 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.
Thus a learning system is characterized by:
Examples: Learning to play chess
T: Play chess
P: Percentage of games won in world tournament
E: Opportunity to play against self or other players
Learning to drive a van
T: Drive on a public highway using vision sensors
P: Average distance traveled before an error (according to human observer)
E: Sequence of images and steering actions recorded during human driving.
The block diagram of a generic learning system which can realize the above definition is shown below:
As can be seen from the above diagram the system consists of the following components: