Girls are doing somersaults.
Gymnasts doing somersaults.
Girls does not imply gymnasts.
exists e1 x1 x2.(Theme(e1,x2) & Actor(e1,x1) & v_do(e1) & n_somersault(x2) & n_girl(x1))
exists e1 x1 x2 x3.(a_topic(x1) & Theme(e1,x3) & Actor(e1,x2) & v_do(e1) & n_somersault(x3) & (x1 = x2) & n_gymnast(x1))