Let V be a finite set of vertices in the plane and S be a finite set of polygonal obstacles, where the vertices of S are in V. We show how to construct a plane 2-spanner of the visibility graph of V with respect to S. As this graph can have unbounded degree, we modify it in three easy-to-follow steps, in order to bound the degree to 7 at the cost of slightly increasing the spanning ratio to 6.

中文翻译：

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存在多边形障碍物的有界扳手

设V为平面中的有限顶点集，S为多边形障碍的有限集，其中S的顶点在V中。我们展示了如何构造V相对于S的可见度图的2平面。由于该图可以具有无界度，因此我们通过三个易于遵循的步骤对其进行了修改，以便将度数绑定到7，但代价是将生成比例略微增加到6。