a small shaggy dog plays with a red ball on the grass.
Someone's pet is playing with a red ball.
Just because a dog is playing with a ball that does not mean they are someone's pet.
exists e1 s1 s2 s3 x1 x2 x3.(n_grass(x3) & with(e1,x2) & on(x2,x3) & n_ball(x2) & a_red(s3) & Theme(s3,x2) & Actor(e1,x1) & v_play(e1) & n_dog(x1) & a_shaggy(s2) & Theme(s2,x1) & a_small(s1) & Theme(s1,x1))
exists e1 s1 x1 x2 x3.(with(e1,x3) & n_ball(x3) & a_red(s1) & Theme(s1,x3) & Actor(e1,x2) & v_play(e1) & n_pet(x2) & of(x2,x1) & n_person(x1))