Dad and his son trying to surf the water
A dad and son play and swim in the waves.
if they are trying to surf the water, that is a type of playing.
exists e1 p1 s1 x1 x2 x3 x4.(n_water(x4) & n_son(x2) & of(x2,x1) & n_male(x1) & ne_nam_dad(x1) & a_topic(s1) & subset_of(x2,s1) & Topic(e1,p1) & Actor(e1,x3) & v_try(e1) & exists e2.(Theme(e2,x4) & Actor(e2,x3) & v_surf(e2)) & (x2 = x3) & subset_of(x1,s1))
exists e1 s1 x1 x2 x3 x4 x5 x6.(n_wave(x6) & a_topic(s1) & subset_of(x2,s1) & subset_of(x5,x2) & in(x5,x6) & n_swim(x5) & subset_of(x3,x2) & Actor(e1,x4) & v_play(e1) & (x3 = x4) & n_son(x3) & subset_of(x1,s1) & n_dad(x1))