Give an example of a relation. Which is
Symmetric and transitive but not reflexive.
Let A = {-7, -8}
Define a relation R on A as:
R = {(-7, -8), (-8, -7), (-7, -7)}
Relation R is not reflexive as (-8, -8) ∉ R
Relation R is symmetric as (-7, -8) ϵ R and (-8, -7) ϵ R
But it is seen that (-7, -8), (-8, -7) ϵ R.
Also, (-7, -7) ϵ R.
⇒ R is transitive.
Therefore, relation R is symmetric and transitive but not reflexive.