A person is surfing in the sea or ocean.
A person is fishing.
The person can't be surfing and fishing at the same time.
exists e1 x1 x2.((n_sea(x2) | n_ocean(x2)) & in(e1,x2) & Actor(e1,x1) & v_surf(e1) & n_person(x1))
exists p1 x1.(exists x2.((x1 = x2) & n_fishing(x2)) & n_person(x1))