On the potential functions for a link diagram
Abstract
Cho and Murakami defined the potential function for a link L in S3 whose critical point, slightly different from the usual sense, corresponds to a boundary-parabolic representation ρ:π1(S3∖L)→PSL2(ℂ). They also showed that the volume and Chern–Simons invariant of ρ can be computed from the potential function with its partial derivatives. In this paper, we extend the potential function to a representation that is not necessarily boundary-parabolic. We show that under a mild assumption it leads us to a combinatorial formula for computing the volume and Chern–Simons invariant of a PSL2(ℂ)-representation of a closed 3-manifold.