A skateboarder jumps another skateboard.
A person is ice-skating.
A skateboarder does not skate on ice so they cannot be ice-skating simultaneously.
exists e1 x1 x2 x3.(n_skateboard(x2) & Theme(e1,x3) & Actor(e1,x1) & v_jump(e1) & n_skateboard(x3) & -(x3 = x2) & n_skateboarder(x1))
exists s1 x1.(Theme(s1,x1) & a_ice-skating(s1) & n_person(x1))