Four people group hugging.
There is a group hug happening.
When a group is hugging there is a group hug happening.
(x)
exists p1 x1 e1 x2 x3 x4.((x1 = x2) & Actor(e1,x4) & v_happen(e1) & (x2 = x4) & n_hug(x2) & of(x2,x3) & n_group(x3))