reflexive is a relationship property that indicates:
A binary relation Rel is called reflexive:
<MATH> \{(a)\in\Bbb A\mid a = a\} \in Rel </MATH>
The relation less than or equal to (<=) on the set of integers {1, 2, 3} is the following set of tuple
<1, 1>,
<1, 2>,
<1, 3>,
<2, 2>,
<2, 3>,
<3, 3>
It is reflexive because the tuples <1, 1>, <2, 2>, <3, 3> are in this relation.
As a matter of fact, this relation is reflexive on any set of numbers (not only integer but also real numbers, …).
Against the <math>R</math> , the relation less than or equal to is the below gray area in <math>R^2</math>
Similarly and because every number is equal to itself, the relation greater than or equal and is equal to on any set of numbers are reflexive.
A few relations:
The gray area is the relation.
In the set of real number, a relation is reflexive if it contains the dotted line y=x
Example: