For a polygon $P$ with holes in the plane, we denote by $\varrho(P)$ the ratio between the geodesic and the Euclidean diameters of $P$. It is shown that over all convex polygons with $h$~convex holes, the supremum of $\varrho(P)$ is between $\Omega(h^{1/3})$ and $O(h^{1/2})$. The upper bound improves to $O(1+\min\{h^{3/4}\Delta,h^{1/2}\Delta^{1/2}\})$ if every hole has diameter at most $\Delta\cdot {\rm diam}_2(P)$; and to $O(1)$ if every hole is a \emph{fat} convex polygon. Furthermore, we show that the function $g(h)=\sup_P \varrho(P)$ over convex polygons with $h$ convex holes has the same growth rate as an analogous quantity over geometric triangulations with $h$ vertices when $h\rightarrow \infty$.
翻译:对于平面内带孔多边形$P$,记$\varrho(P)$为$P$的测地直径与欧氏直径之比。研究表明:在所有含$h$个凸孔的多边形中,$\varrho(P)$的上确界介于$\Omega(h^{1/3})$与$O(h^{1/2})$之间。若每个孔的直径不超过$\Delta\cdot {\rm diam}_2(P)$,则该上界可改进为$O(1+\min\{h^{3/4}\Delta,h^{1/2}\Delta^{1/2}\})$;若每个孔均为\textit{胖}凸多边形,则上界可改进为$O(1)$。此外,我们证明当$h\rightarrow \infty$时,关于含$h$个凸孔的凸多边形定义的函数$g(h)=\sup_P \varrho(P)$与关于含$h$个顶点的几何三角剖分类比量具有相同的增长率。