we must also check the universe levels when applying the optimization for
constraints of the form:
f.{l_1 ... l_k} a_1 ... a_n =?= f.{l_1' ... l_k'} b_1 ... b_n
The optimization tries to avoid unfolding f if we can establish that
a_i is definitionally equal to b_i for each i in [1, n]
closes#581
