Minimizing Visible Edges in Polyhedra.

We prove that, given a polyhedron P in R 3 , every point in R 3 that does not see any vertex of P must see eight or more edges of P , and this bound is tight. More generally, this remains true if P is any finite arrangement of internally disjoint polygons in R 3 . We also prove that every point in R 3 can see six or more edges of P (possibly only the endpoints of some these edges) and every point in the interior of P can see a positive portion of at least six edges of P . These bounds are also tight. [ABSTRACT FROM AUTHOR]