premise: a surfer is riding the waves whilst another surfer sits on his board waiting.
hypothesis: There are people surfing.
explanation_1: A surfer riding waves infers that people are surfing.
explanation_2: Riding the waves and sitting on a board are parts of surfing.
explanation_3: A surfer riding the waves is surfing.
premise_logic: exists e3 e1 e2 x1 x2 x3 x4 x5 x6 x7.(n_waiting(x6) & of(x6,x7) & n_board(x7) & of(x6,x3) & n_male(x3) & n_wave(x3) & Theme(e3,x4) & Actor(e3,x1) & v_whilst(e3) & on(e2,x6) & Actor(e2,x5) & v_sit(e2) & (x4 = x5) & n_surfer(x4) & -(x4 = x1) & n_surfer(x1) & n_surfer(x1) & Theme(e1,x3) & Actor(e1,x2) & v_ride(e1) & (x1 = x2))
hypothesis_logic: exists p1 x1 e1 x2 x3.((x1 = x2) & Actor(e1,x3) & v_surf(e1) & (x2 = x3) & n_people(x2))