Solution;
(iii) Given R = {(x, y): x is wife of y}
Now we have to check whether the relation R is reflexive, symmetric and transitive.
First let us check whether the relation is reflexive:
Let x be an element of R.
Then, x is wife of x cannot be true.
⇒ (x, x) ∉R
So, R is not a reflexive relation.
Symmetric relation:
Let (x, y) ∈R
⇒ x is wife of y
⇒ x is female and y is male
⇒ y cannot be wife of x as y is husband of x
⇒ (y, x) ∉R
So, R is not a symmetric relation.
Transitive relation:
Let (x, y) ∈R, but (y, z) ∉R
Since x is wife of y, but y cannot be the wife of z, y is husband of x.
⇒ x is not the wife of z
⇒(x, z) ∈R
So, R is a transitive relation.
(iv) Given R = {(x, y): x is father of y}
Now we have to check whether the relation R is reflexive, symmetric and transitive.
Reflexivity:
Let x be an arbitrary element of R.
Then, x is father of x cannot be true since no one can be father of himself.
So, R is not a reflexive relation.
Symmetry:
Let (x, y) ∈R
⇒ x is father of y
⇒ y is son/daughter of x
⇒ (y, x) ∉R
So, R is not a symmetric relation.
Transitivity:
Let (x, y) ∈R and (y, z) ∈R.
Then, x is father of y and y is father of z
⇒ x is grandfather of z
⇒ (x, z) ∉R
So, R is not a transitive relation.