Arm-strokes from swimmers who are racing in the pool.
No one is in the water.
Swimmers can not be racing in the pool if no one is in the water.
exists e1 x1 x2 x3 x4.(n_pool(x4) & a_topic(x1) & from(x1,x2) & in(e1,x4) & Actor(e1,x3) & v_race(e1) & (x2 = x3) & n_swimmer(x2) & n_arm-stroke(x1))
exists x2.(n_water(x2) & -exists p1 x1.(in(x1,x2) & n_one(x1)))