Critical point theorems and Whitney duality for polyhedral surfaces (Q1317035)

A Whitney duality theorem for the tangential and normal Stiefel-Whitney classes of a surface in \(\mathbb{R}^ 3\) or \(\mathbb{R}^ 4\) can be geometrically expressed in terms of singularities of linear projections to lower dimensional subspaces, as was shown by T. Banchoff and C. McCrory. In this paper the author gives a polyhedral version of this result. It relies on a thorough study of the critical behavior of polyhedral functions which is ``more concentrated, more complicated and more stable'' (from the paper).