SETS AND FUNCTONS

Definition:
 A set is a collection of well-defined objects. The objects
in a set are called elements or members of that set.
Definition:
(i) A set is said to be a finite set if it contains only a finite number of elements in it.
(ii) A set which is not finite is called an infinite set.
 Definition:
(i) If a set X is finite, then we define the cardinality of X to be the number of
elements in X . Cardinality of a set X is denoted by n(X) .
(ii) If a set X is infinite, then we denote the cardinality of X by a symbol 3.