A batter swings while the catcher and umpire look on.
the batter swings at the ball
If a batter swings while the catcher and umpire look on, it follows that the batter is swinging at the ball.
(x)
exists x1 x2 x3.(n_ball(x3) & n_swing(x1) & of(x1,x2) & n_batter(x2) & a_topic(x1) & at(x1,x3))