Determine whether each of the following relations are reflexive, symmetric and transitive:
(ii) Relation R in the set N of natural numbers defined as
R = {(x, y): y = x + 5 and x < 4}
Here, A=N, the set of natural numbers and R={(x,y);y=x+5,x<4}
={(x,x+5):xϵN and x < 4}
={(1,6),(2,7),(3,8)}
(a)For reflexive x,xϵR∀x putting y=x,x≠y+5⇒(1,1)/ϵR. So, R is not reflexive.
(b)For symmetrical (x,y)ϵR⇒(y,x)ϵR putting y =x+5, then x≠y+5⇒(1,6)ϵR but (6,1)/ϵR. So, R is not symmetric.
(c)For transitivity (x,y)ϵR,(y,z)ϵR⇒(x,z)ϵR if y =x+5, z=y+5, then z≠x+5. Since, (1,6)ϵR and there is no order pair in R which has 6 as the first element same in the case for (2,7)and (3,8). So, R is not transitive.