A train conductor looks out the window of his train while smiling.
A train conductor is smiling.
To look out the window while smiling, the train conductor must be smiling. This is a necessary, but not sufficient, condition.
exists e1 e2 s1 x1 x2 x3.(n_male(x3) & n_window(x3) & while(e1,e2) & Actor(e2,x1) & v_smile(e2) & a_out(s1) & Manner(e1,s1) & Theme(e1,x3) & Actor(e1,x1) & v_look(e1) & of(x3,x2) & n_train(x2) & n_train(x2) & of(x2,x3) & n_conductor(x1) & of(x1,x2))
exists e1 x1 x2.(Actor(e1,x1) & v_smile(e1) & n_conductor(x1) & of(x1,x2) & n_train(x2))