A person does a back flip into the water.
Someone does a back flip into the water.
A person by existing is someone, and they do a flip.
exists e1 s1 x1 x2 x3.(n_water(x3) & into(e1,x3) & Theme(e1,x2) & Actor(e1,x1) & v_do(e1) & n_flip(x2) & a_back(s1) & Theme(s1,x2) & n_person(x1))
exists e1 s1 x1 x2 x3.(n_water(x3) & into(e1,x3) & Theme(e1,x2) & Actor(e1,x1) & v_do(e1) & n_flip(x2) & a_back(s1) & Theme(s1,x2) & n_person(x1))