
Solution Manual
Author: Uma Shanker Gupta and ISBN: 978-93-325-2139-1
A-8
14. A = {a, b, c}. The relation matrix is
M
a
b
c
R
=
This gives
R = {(a, a), (b, b), (c, c), (a, b), (b, a)}
Clearly R is reflexive, symmetric and transitive and hence R is an equivalence relation.
15. For the given digraph, the relation R is
R = {(a, a), (b, b), (c, c), (a, b), (b, c), (c, a)}
The relation R is reflexive as (a, a), (b, b), (c, c) ∈ R
It is not symmetric (b, a) ∉ R, (a, c) ∉ R, (c, b) ∉ R
Now, (a, b) ∈ R and (b, c) ∈ R
⇒
(a, c) ∈ R
which shows that R is not transitive. Thus, R is not an equivalence relation.
16. Let P