The dog retrieves the branch from the water.
The dog grabs a stick
Retrieves and grabs could mean the same thing.  A branch and a stick could be the same thing.
exists e1 x1 x2 x3.(n_water(x3) & n_branch(x2) & n_dog(x1) & from(e1,x3) & Theme(e1,x2) & Actor(e1,x1) & v_retrieve(e1))
exists e1 x1 x2.(n_dog(x1) & Theme(e1,x2) & Actor(e1,x1) & v_grab(e1) & n_stick(x2))