A man is on a surfboard surfing the waves and catching good air.
A man on a surfboard is surfing.
Surfing on the waves and catching good air is the description or longer explanation of the activity "surfing".
exists e1 e2 p1 s1 x1 x2 x3.(n_wave(x2) & for(p1,e2) & Theme(e2,x3) & Actor(e2,x1) & v_catch(e2) & n_air(x3) & a_good(s1) & Theme(s1,x3) & for(p1,e1) & Theme(e1,x2) & Actor(e1,x1) & v_surf(e1) & exists x4.(on(x1,x4) & n_surfboard(x4)) & n_man(x1))
exists e1 x1 x2.(Actor(e1,x1) & v_surf(e1) & on(x1,x2) & n_surfboard(x2) & n_man(x1))