Tourists board a Vietnamese skiff for a river tour.
the tourists are at home
The tourists cannot be on a river tour and be at home simultaneously.
all x1 s1.((n_skiff(x1) & a_vietnamese(s1) & Theme(s1,x1)) -> exists x2 x3 x4 x5.(a_topic(x2) & for(x2,x4) & n_tour(x4) & of(x4,x5) & n_river(x5) & for(x2,x1) & n_board(x2) & (x2 = x3) & ne_nam_tourists(x3)))
exists p1 x1.(n_tourist(x1) & exists x2.(at(x1,x2) & n_home(x2)))