premise: A boy and a girl walk through the city.
hypothesis: A boy and a girl are walking outside.
explanation_1: If you are walking through the city, then you are walking outside.
explanation_2: They must be outside to walk through the city.
explanation_3: Sentence 1 indicates the couple is walking through a city while sentence 2 states they are outside but does not specify a city setting.  In sentence 2 the couple could be anywhere outside.
premise_logic: exists s1 x1 x2 x3 x4.(n_city(x4) & a_topic(s1) & subset_of(x2,s1) & through(x2,x4) & n_walk(x2) & of(x2,x3) & n_girl(x3) & subset_of(x1,s1) & n_boy(x1))
hypothesis_logic: exists e1 s1 x1 x2 x3.(a_outside(s1) & Manner(e1,s1) & Actor(e1,x1) & v_walk(e1) & subset_of(x3,x1) & n_girl(x3) & subset_of(x2,x1) & n_boy(x2))
premise_sim: exists s1 x1 x2 x3 x4.(through(x2,x4) & subset_of(x2,s1) & subset_of(x1,s1) & of(x2,x3) & n_walk(x2) & n_girl(x3) & n_city(x4) & n_boy(x1) & a_topic(s1))
hypothesis_sim: exists e1 s1 x1 x2 x3.(v_walk(e1) & subset_of(x3,x1) & subset_of(x2,x1) & n_girl(x3) & n_boy(x2) & a_outside(s1) & Manner(e1,s1) & Actor(e1,x1))