$\newcommand{\eps}{\varepsilon}$ We observe that a $(1-\eps)$-approximation algorithm to Independent Set, that works for any induced subgraph of the input graph, can be used, via a polynomial time reduction, to provide a $(1+\eps)$-approximation to Vertex Cover. This basic observation was made before, see [BHR11]. As a consequence, we get a PTAS for VC for unweighted pseudo-disks, QQPTAS for VC for unweighted axis-aligned rectangles in the plane, and QPTAS for MWVC for weighted polygons in the plane. To the best of our knowledge all these results are new.
翻译:$\newcommand{\eps}{\varepsilon}$ 我们观察到,若存在一个针对输入图任意导出子图的 $(1-\eps)$ 近似算法求解独立集问题,则可通过多项式时间归约,得到一个求解顶点覆盖问题的 $(1+\eps)$ 近似算法。这一基本观察前人已有提及,参见[BHR11]。由此,我们得到了针对无权伪圆盘的顶点覆盖问题的PTAS,针对平面内无权轴对齐矩形的顶点覆盖问题的QQPTAS,以及针对平面内加权多边形的最大权顶点覆盖问题(MWVC)的QPTAS。据我们所知,所有这些结果均为首次提出。