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

翻译：我们证明，给定 $\mathbb{R}^3$ 中的一个多面体 $\mathcal P$，$\mathbb R^3$ 中任何看不到 $\mathcal P$ 任一顶点的点，必须能看到 $\mathcal P$ 的八条或更多条边，并且这一下界是紧的。更一般地，若 $\mathcal P$ 是 $\mathbb{R}^3$ 中内部不相交多边形的任意有限排列，该结论仍然成立。我们还证明，$\mathbb{R}^3$ 中的每一点都能看到 $\mathcal{P}$ 的六条或更多条边（可能仅包含其中某些边的端点），并且 $\mathcal{P}$ 内部的每一点能看到 $\mathcal{P}$ 的至少六条边的正部分。这些下界也是紧的。