However, a relation R in the set {1, 2, 3, 4} defined by R
= {(a, b) : b = a + 1} is also expressed as a R b if and only if
b = a + 1 by many authors We may also use this notation, as and when convenient If (a, b) ∈ R, we say that a is related to b and we denote it as a R b One of the most important relation, which plays a significant role in Mathematics,
is an equivalence relation