A surfboarder catches the waves.
a person is skateboarding
surfboarder is not a skateboarder
exists e1 x1 x2.(n_wave(x2) & Theme(e1,x2) & Actor(e1,x1) & v_catch(e1) & n_surfboarder(x1))
exists e1 x1.(Actor(e1,x1) & v_skateboard(e1) & n_person(x1))