In this paper, we study the problem of whether a polyhedron can be obtained from a net by folding along the creases. We show that this problem can be solved in polynomial time if the dihedral angle at each crease is given, and it becomes NP-hard if these angles are unknown. We also study the case when the net has rigid faces that should not intersect during the folding process. (c) 2004 Elsevier B.V. All rights reserved.
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