This paper defines two new extrinsic curvature quantities on the corner of a
four-dimensional Riemannian manifold with corner. One of these is a pointwise
conformal invariant, and the conformal transformation of the other is governed by a
new linear second-order pointwise conformally invariant partial differential
operator. The Gauss–Bonnet theorem is then stated in terms of these quantities.
Keywords
Gauss–Bonnet with corners, conformal geometry, corners,
corner operators, manifolds with edges