premise: A man and his two sons purchase food.
hypothesis: They are shopping.
explanation_1: Purchase food is shopping.
explanation_2: They is a term that denotes a man and his two sons.  People who purchase food are doing a shopping.
explanation_3: a man and his two sons are shopping a food
premise_logic: exists s1 x1 x2 x3 x4.(a_topic(s1) & subset_of(x2,s1) & n_food(x2) & of(x2,x4) & n_purchase(x4) & of(x2,x3) & n_son(x3) & card_eq_2(x2) & of(x2,x1) & n_male(x1) & subset_of(x1,s1) & n_man(x1))
hypothesis_logic: exists p1 x1.(n_thing(x1) & exists x2.((x1 = x2) & n_shopping(x2)))