A child sleds.
a dog eating a treat
There can be either a child or a dog but not both, and one cannot be eating a treat or be one who sleds simultaneously.
exists x1 x2.(a_topic(x1) & n_sled(x1) & of(x1,x2) & n_child(x2))
exists e1 x1 x2 x3.(a_topic(x1) & Theme(e1,x3) & Actor(e1,x2) & v_eat(e1) & n_treat(x3) & (x1 = x2) & n_dog(x1))