Two dogs running in a field of dry grass on a clear day.
Two dogs are chasing a frissbe.
The first sentence does not explain why the dogs are running.  There are numerous reasons for dogs to run besides chasing a frissbe.
exists e1 s1 s2 x1 x2 x3 x4 x5.(a_topic(x1) & on(e1,x5) & n_day(x5) & a_clear(s2) & Theme(s2,x5) & in(e1,x3) & of(x3,x4) & n_grass(x4) & a_dry(s1) & Theme(s1,x4) & n_field(x3) & Actor(e1,x2) & v_run(e1) & (x1 = x2) & n_dog(x1) & card_eq_2(x1))
exists e1 x1 x2.(Theme(e1,x2) & Actor(e1,x1) & v_chase(e1) & n_frissbe(x2) & n_dog(x1) & card_eq_2(x1))