premise: A group of people are sight seeing and taking pictures.
hypothesis: the group is on vacation
explanation_1: People do not need to be on vacation to go sight seeing.
explanation_2: A group of people may be signt seeing or taking pictures being not on vacation but on a business trip or cultural tour.
explanation_3: Just because a  group of people are sight seeing and taking pictures does not mean they are on vacation.
premise_logic: exists e2 e1 p1 x1 x2 x3 x4.(for(p1,e2) & Theme(e2,x4) & Actor(e2,x1) & v_take(e2) & n_picture(x4) & for(p1,e1) & Theme(e1,x3) & Actor(e1,x1) & v_see(e1) & n_picture(x3) & exists x5.((x1 = x5) & n_sight(x5)) & of(x1,x2) & n_people(x2) & n_group(x1))
hypothesis_logic: exists p1 x1.(n_group(x1) & exists x2.(on(x1,x2) & n_vacation(x2)))