An astronaut and a diver are underwater.
Two explorers are underwater.
An astronaut and a diver are two people and they are explorers of space and the deep sea respectively
exists p1 x1 x2 x3.(exists x4.((x1 = x4) & n_underwater(x4)) & subset_of(x3,x1) & n_diver(x3) & subset_of(x2,x1) & n_astronaut(x2))
exists s1 x1.(Theme(s1,x1) & a_underwater(s1) & n_explorer(x1) & card_eq_2(x1))