  We consider the problem of cutting a set of edges on a polyhedral manifold
surface, possibly with boundary, to obtain a single topological disk,
minimizing either the total number of cut edges or their total length. We show
that this problem is NP-hard, even for manifolds without boundary and for
punctured spheres. We also describe an algorithm with running time n^{O(g+k)},
where n is the combinatorial complexity, g is the genus, and k is the number of
boundary components of the input surface. Finally, we describe a greedy
algorithm that outputs a O(log^2 g)-approximation of the minimum cut graph in
O(g^2 n log n) time.
