Let A = {a, b, c}, B = {d, e, f}, C = {g, h, k}, L = {b, c}, M= {d, e} and N = {g, k}.
verify that .
A x B x C = {(a, d, g), (a, d, h), (a, d, k), (a, e, g), (a, e, h), (a, e, k), (a, f, g), (a, f, h), (a, f, k), (b, d, g), (b, f, h), (b, f, k), (c, d, g), (c, d, h), (c, d, k), (c, e, g), (c, e, h), (c, e, k), (c, f, g), (c, f, h), (c, f k) ...(i)
L x M x N = {(b, d),m (b, e), (c, d), (c, e)x (g, k)}
= {(b, d, g), (b, d, k), (b, e, g), (b, e, k), (c, d, g), (c, d , k), (c, e, g), c, e, ,k) ...(ii)
From (i) a nd (ii), we observe that every member of L X M x N is also a member of A X B X C
∴
Also, n(L x M x N) < n(A x B x C)
Hence,