Linear Time Algorithm
Booth and Lueker, 1976, designed an algorithm that runs in time O(n+m+s).
- n is the size of the universe, m is the number of sets, and s is the sum of the sizes of the sets.
It requires a novel data structure called the PQ tree that represents a set of orderings.
PQ trees can also be used to test whether an undirected graph is planar.