A husband and wife walk by a marketplace while traveling.
A couple are riding in a boat.
They can't ride a boat and walk at the same time.
exists e1 e2 x1 x2 x3 x4.(while(e1,e2) & Actor(e2,x1) & v_travel(e2) & Actor(e1,x4) & n_marketplace(x4) & Theme(e1,x1) & v_walk(e1) & subset_of(x3,x1) & n_wife(x3) & subset_of(x2,x1) & n_husband(x2))
exists e1 x1 x2.(in(e1,x2) & n_boat(x2) & Actor(e1,x1) & v_ride(e1) & n_couple(x1))