Two dogs, both wearing collars, are playing with one another in the grass.
Dogs are playing together in the grass.
Two dogs is a rephrasing of dogs and playing with one another implies they are playing together.
exists e1 e2 s1 x1 x2 x3 x4 x5 x6.(n_grass(x6) & in(e2,x6) & with(e2,x5) & n_thing(x5) & card_eq_1(x5) & a_another(s1) & Theme(s1,x5) & Actor(e2,x1) & v_play(e2) & rel(x1,x2) & Theme(e1,x4) & Actor(e1,x3) & v_wear(e1) & n_collar(x4) & (x2 = x3) & n_thing(x2) & n_dog(x1) & card_eq_2(x1))
exists e1 s1 x1 x2.(n_grass(x2) & in(e1,x2) & a_together(s1) & Manner(e1,s1) & Actor(e1,x1) & v_play(e1) & n_dog(x1))