lRosalind B. Marimont
A new method of checking
the consistency of precedence matrices
Journal of the ACM 6, 164-171,
1959
lPruning away any arcs that point to leaves does not change the cyclic/acyclic
nature of the graph.
lPruning such arcs may produce additional leaves.
lPrune until no further pruning is possible:
lIf the result is empty, the original graph was acyclic.
lIf not, it was cyclic.