A group of tourists are exploring the sight.
The tourists are part of a tour group.
You can not infer they are on a tour.
exists e1 x1 x2 x3.(n_sight(x3) & Theme(e1,x3) & Actor(e1,x1) & v_explore(e1) & of(x1,x2) & n_tourist(x2) & n_group(x1))
exists p1 x1.(n_tourist(x1) & exists x2 x3 x4.((x1 = x2) & of(x2,x3) & n_group(x3) & of(x3,x4) & n_tour(x4) & n_part(x2)))