Man taking a walk by himself.
The man is contemplating to himself.
Taking a walk does not imply contemplating.
exists e1 x1 x2 x3.(a_topic(x1) & Theme(e1,x3) & Actor(e1,x2) & v_take(e1) & by(x3,x1) & n_male(x1) & n_walk(x3) & (x1 = x2) & n_man(x1))
exists e1 x1.(n_male(x1) & n_man(x1) & to(e1,x1) & Actor(e1,x1) & v_contemplate(e1))