The subset E is called the equivalence class containing zero and is denoted by
[0] Similarly, O is the equivalence class containing 1 and is denoted by [1] Note that
[0] ≠ [1], [0] = [2r] and [1] = [2r + 1], r ∈ Z Infact, what we have seen above is true
for an arbitrary equivalence relation R in a set X