Definition : A relation is a set of ordered pairs.
Notation : If R stands for the relation " is a divisor of " then we can write 6 R 30 which means 6 is a divisor of 30. If A and B are two sets, then we can say that a relation from A to B is a non empty sub set of A ´ B. Hence A R B Î A ´ B.
Roster method : In this method, a relation is represented as a set of ordered pairs.
For example { ( 1, 1 ) , ( 1, 2 ) , ( 2, 2 ) , ( 2, 2 ) }
Rule method: In this method, the rule which gives a relation is stated.
For example { ( x, y )  x = y Ù x Î N }
Graph method: In this method a graph of the given relation is drawn.
Arrow diagram: In this method the relation is shown by arrows from the first
component to the second one.
Set A is a Capital of (R) Set B

Index
6.1 Relations 6.2 Functions 6.3 Variation
Chapter 7
