A white pitcher throwing the ball.
A man throws a ball.
Both sentences speak about a man throwing a ball.
exists e1 s1 x1 x2 x3.(n_ball(x3) & a_topic(x1) & Theme(e1,x3) & Actor(e1,x2) & v_throw(e1) & (x1 = x2) & n_pitcher(x1) & a_white(s1) & Theme(s1,x1))
exists e1 x1 x2.(Theme(e1,x2) & Actor(e1,x1) & v_throw(e1) & n_ball(x2) & n_man(x1))