A man working on his computer.
A man sits at a computer.
The man is working on his computer so he must be sitting at a computer.
exists e1 x1 x2 x3.(a_topic(x1) & on(e1,x3) & n_computer(x3) & of(x3,x1) & n_male(x1) & Actor(e1,x2) & v_work(e1) & (x1 = x2) & n_man(x1))
exists e1 x1 x2.(at(e1,x2) & n_computer(x2) & Actor(e1,x1) & v_sit(e1) & n_man(x1))