A boy in black waves his arms while other people are behind him on a field.
A boy is on a baseball field.
He may be on a field, but that doesn't mean that it is a baseball field necessarily.
(-x)
exists p1 x1.(exists x2 x3.(on(x1,x2) & n_field(x2) & of(x2,x3) & n_baseball(x3)) & n_boy(x1))