Abstract
In this paper, we show that the disjoint union of two cordial graphs one of them is of even size is cordial and the join of two cordial graphs both are of even size or one of them is of even size and one of them is of even order is cordial. We also show that Cm boolean OR C(n) is cordial if and only if m+n not equivalent to 2 (mod 4) and mC(n) is cordial if and only if mn not equivalent to 2 (mod 4) and for m, n 3, C(m) + Cn is cordial if and only if (m, n) (3, 3) and {m,n} * (0, 2) (mod 4). Finally, we discuss the cordiality of P(n)(k).