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<speaker>Andrew D. Hwang</speaker>
<credentials>College of the Holy Cross</credentials>
<description>A polyhedron comprises a finite collection of polygons, called faces, that are joined so that any two faces meet along an
edge, at a vertex, or not at all. A closed polyhedron has no
free edges; its topological type is determined by two invariants, its
genus and orientability.
Near a vertex, a polyhedron may be impossible to flatten; the angular
defect at a vertex plays the role of curvature. Remarkably, the
total angular defect ("total curvature") of a polyhedron depends
only on its topological type. We'll see why this is true, and use the
result to investigate the topology of specific polyhedra, such as
Kepler's great dodecahedron.
(Refreshments at 3:30 in Mudd 412A)</description>
<sponsor>Prof. Jan Holly</sponsor>