premise: Four people walk across stepping stones in a body of water.
hypothesis: Three people are riding in a boat.
explanation_1: Either the people walk, or they are riding.
explanation_2: There can be three or four people.
explanation_3: There are either four people or three people.  The people cannot be walking across stepping stones and riding in a boat at the same time.
premise_logic: exists e1 e2 s1 x1 x2 x3 x4.(for(e1,e2) & Theme(e2,x2) & Actor(e2,x1) & v_step(e2) & in(x2,x3) & of(x3,x4) & n_water(x4) & n_body(x3) & n_stone(x2) & a_across(s1) & Manner(e1,s1) & Actor(e1,x1) & v_walk(e1) & n_people(x1) & card_eq_4(x1))
hypothesis_logic: exists e1 x1 x2.(in(e1,x2) & n_boat(x2) & Actor(e1,x1) & v_ride(e1) & n_people(x1) & card_eq_3(x1))
premise_sim: exists e1 e2 s1 x1 x2 x3 x4.(v_walk(e1) & v_step(e2) & of(x3,x4) & n_water(x4) & n_stone(x2) & n_people(x1) & n_body(x3) & in(x2,x3) & for(e1,e2) & card_eq_4(x1) & a_across(s1) & Theme(e2,x2) & Manner(e1,s1) & Actor(e2,x1) & Actor(e1,x1))
hypothesis_sim: exists e1 x1 x2.(v_ride(e1) & n_people(x1) & n_boat(x2) & in(e1,x2) & card_eq_3(x1) & Actor(e1,x1))