The sky is blue
There are clouds in the sky
Clouds in the sky does not necessarily mean the sky is blue.
exists s1 x1.(n_sky(x1) & Theme(s1,x1) & a_blue(s1))
exists p1 x1 x2.(n_sky(x2) & in(p1,x2) & exists x3.((x1 = x3) & n_cloud(x3)))