premise: A man is on the back of his friend.
hypothesis: A man is on the back of his friend in the swimming pool.
explanation_1: You can not infer he is in the swimming pool.
explanation_2: A man can be on the back of his friend in a location besides in a swimming pool.
explanation_3: A man can be on his friend's back and not be swimming or in a pool.
premise_logic: exists p1 x1 x2 x3.(n_friend(x3) & of(x3,x2) & n_male(x2) & n_back(x2) & on(x1,x2) & of(x2,x3) & n_man(x1))
hypothesis_logic: exists p1 x1 x2 x3 x4 x5.(n_pool(x4) & of(x4,x5) & n_swimming(x5) & n_friend(x3) & of(x3,x2) & n_male(x2) & n_back(x2) & on(x1,x2) & of(x2,x3) & in(x3,x4) & n_man(x1))