P327: Enumeration of all spanning trees of a plane

P327: Enumeration of all spanning trees of a plane
Input:
A point set $P$.
Output:
All spanning trees of $P$.
Complexity:
$O(|P|^3N)$ total time and $O(|P|)$ space.
Comment:
$N$ is the number of solutions.
Reference:
[Avis1996] (Bibtex)