A dog is chewing on a big branch.
a cat chews on a branch.
A dog is not a cat.
exists e1 s1 x1 x2.(on(e1,x2) & n_branch(x2) & a_big(s1) & Theme(s1,x2) & Actor(e1,x1) & v_chew(e1) & n_dog(x1))
exists e1 x1 x2.(on(e1,x2) & n_branch(x2) & Actor(e1,x1) & v_chew(e1) & n_cat(x1))