Many surfers are sitting on their surfboards in the calm ocean.
A group of surfers is waiting to catch a wave
To surf you need a wave, if surfers are sitting on their surfboards and the ocean is calm, they must be waiting.
exists e1 s1 x1 x2 x3.(n_ocean(x3) & a_calm(s1) & Theme(s1,x3) & in(e1,x3) & on(e1,x2) & n_surfboard(x2) & of(x2,x1) & n_thing(x1) & Actor(e1,x1) & v_sit(e1) & n_surfer(x1) & n_quantity(x1))
exists e1 p1 x1 x2.(Topic(e1,p1) & Actor(e1,x1) & v_wait(e1) & exists e2 x3.(Theme(e2,x3) & Actor(e2,x1) & v_catch(e2) & n_wave(x3)) & of(x1,x2) & n_surfer(x2) & n_group(x1))