Before revision:  Moreover, NVD (P) and FVD (P ) can be computed in O(n\log n) time using O(n) space [Preparata, Shamos, Springer'85].
After revision:  Moreover, NVD and FVD for P can be computed in O(n\log n) time using O(n) space [Preparata, Shamos, Springer'85].