There is a man surfing at night.
A person on a surfboard in the evening.
The person on the surfboard in the evening is probably the man still surfing at night.
exists p1 x1 x2 x3 x4.((x1 = x2) & at(x2,x4) & n_night(x4) & n_surfing(x2) & of(x2,x3) & n_man(x3))
exists x1 x2 x3.(n_evening(x3) & a_topic(x1) & on(x1,x2) & in(x2,x3) & n_surfboard(x2) & n_person(x1))