A shoe shiner waits for customers.
A shoe shiner is present.
A shoe shiner has to be present while he waits for customers
exists x1 x2 x3 x4.(a_topic(x1) & for(x1,x4) & n_customer(x4) & n_wait(x1) & of(x1,x3) & n_shiner(x3) & of(x1,x2) & n_shoe(x2))
exists s1 x1 x2.(Theme(s1,x1) & a_present(s1) & n_shiner(x1) & of(x1,x2) & n_shoe(x2))