The above expression is obtained by using , among other things , the remarkable gauge covariant Kaehler identity igr s ( x)D Ac xrD Ac x s − ig rs ( x)D Ac x r D Ac xs = x * A ω . ( 5.18 ) This calculation shows the topological nature of the theory . All dependence on the metric of Σ and the background connection A 0 is again buried inside the gauge fermion Ψ P W . The topological quantum field correlators , therefore , are going to be independent from these data .