Determine whether each of the following relations are reflexive, symmetric and transitive:
(iv) Relation R in the set Z of all integers defined as R = {(x, y): x − y is an integer}
For reflexive put y=x, x-x =0 which is an integer for all xϵZ. So, R is reflexive on Z.
(b)For symmetry let (x,y)ϵR, then (x-y)is an integer λ and also y−x=−λ[∵λϵZ⇒−λϵZ]
∴y−x is an integer ⇒(y,x)ϵR. SO, R is symmetric.
(c)For transitivity let (x,y) belongs R and (y,z)ϵR∴x−y = integer and y-z = integer, then x-z is also an integer
∴(x,z)ϵR. So, R is transitive