Prove or DisproveSolutionconsider that we have a A be arbitr
Prove or Disprove.
Solution
consider that we have a A be arbitrary.
as given R and S are equivalence relations on A so they are reflexive,
hence we can say that (a, a) R and (a, a) S.
so (a, a) R S
hence we say that R S is reflexive.
now consider that a, b A are such that (a, b) R S.
so we can say that (a, b) R and (a, b) S.
also if R and S are symmetric, it follows that (b, a) R and (b, a) S.
as (b, a) R S, R S is symmetric.
now suppose a, b, c A are such that (a, b),(b, c) R S.
then we can say that (a, b),(b, c) R and (a, b),(b, c) S.
also if R is transitive, (a, b),(b, c) R implies that (a, c) R.
as S is transitive, (a, b),(b, c) S implies that (a, c) S.
so we can say that (a, c) R and (a, c) S,
so that (a, c) R S.
so we have verified R S is transitive.
as R S is reflexive, symmetric and transitive, and hence R S is an equivalence relation on A
