Construction workers are digging a ditch.
Construction workers preparing to install a pipe system.
Not all ditches are dug to install a pipe system.
exists e1 x1 x2 x3.(Theme(e1,x3) & Actor(e1,x1) & v_dig(e1) & n_ditch(x3) & n_worker(x1) & of(x1,x2) & n_construction(x2))
exists e1 p1 x1 x2.(Topic(e1,p1) & Actor(e1,x1) & v_prepare(e1) & exists e2 x3 x4.(Theme(e2,x3) & Actor(e2,x1) & v_install(e2) & n_system(x3) & of(x3,x4) & n_pipe(x4)) & n_worker(x1) & of(x1,x2) & n_construction(x2))