premise: a group of four people conversing next to a bus
hypothesis: Friends discuss their trip before the tour starts.
explanation_1: It is possible for people to converse with each other without being friends. People can converse for any reason and not just to discuss a trip. Not all bus rides are for tours.
explanation_2: Conversing doesn't imply talking about a trip and a bus doesn't imply a tour.
explanation_3: A group does not necessarily have to be friends.
premise_logic: exists e1 x1 x2 x3 x4.(a_topic(x1) & of(x1,x2) & to(e1,x4) & n_bus(x4) & r_next(e1) & Actor(e1,x3) & v_converse(e1) & (x2 = x3) & n_people(x2) & card_eq_4(x2) & n_group(x1))
hypothesis_logic: exists e1 p1 x1 x2 x3.(n_tour(x3) & exists e2.(Actor(e2,x3) & v_start(e2)) & before(e1,p1) & Theme(e1,x2) & Actor(e1,x1) & v_discuss(e1) & n_trip(x2) & of(x2,x1) & n_thing(x1) & n_friend(x1))