Young protesters outside holding signs.
A dog is playing with a toy.
Subjects are young protesters and a dog, while not contradictory on their own, if the subject is meant to be the same, they are not.
exists e1 s1 x1 x2.(a_topic(x1) & outside(x1,x2) & n_sign(x2) & Actor(e1,x2) & v_hold(e1) & n_protester(x1) & a_young(s1) & Theme(s1,x1))
exists e1 x1 x2.(with(e1,x2) & n_toy(x2) & Actor(e1,x1) & v_play(e1) & n_dog(x1))