论文标题
外平面图中的最大重量分离路径通过单树切割近似器
Maximum Weight Disjoint Paths in Outerplanar Graphs via Single-Tree Cut Approximators
论文作者
论文摘要
自1997年以来,最大的分离路径问题一直存在稳定的进步。实现可拖动结果通常需要专注于放松,例如:(i)允许解决方案中的某些边缘充血,(ii)仅考虑单位重量(基数)设置,(iii)仅需要所选需求的分数路由(全或noth flow设置)。对于一般形式(没有拥塞,一般权重,整体路由),边缘路径路径({\ sc edp})甚至是恒星的单位容量树的情况,即Edmonds提供了精确算法的最大匹配问题。对于一般的电容树,garg,vazirani,Yannakakis表明问题是APX-HARD和CHEKURI,Mydlarz,Shepherd提供了$ 4 $ approximation。从本质上讲,这是唯一一个以\ textsc {edp}的常规形式知道常数近似的设置。我们通过在外面平面图中给出通用形式\ textsc {edp}的恒定因素近似算法来扩展结果。该算法的关键组件是找到一个{\ em单树} $ O(1)$ $ cut Outerplanar图的近似值。以前,$ O(1)$切割的近似值仅通过树木的分布来知道,这些近似值隐含地基于Gupta,Newman,Rabinovich和Sinclair对远距离树嵌入的结果,并结合了Anderson和Feige的结果。
Since 1997 there has been a steady stream of advances for the maximum disjoint paths problem. Achieving tractable results has usually required focusing on relaxations such as: (i) to allow some bounded edge congestion in solutions, (ii) to only consider the unit weight (cardinality) setting, (iii) to only require fractional routability of the selected demands (the all-or-nothing flow setting). For the general form (no congestion, general weights, integral routing) of edge-disjoint paths ({\sc edp}) even the case of unit capacity trees which are stars generalizes the maximum matching problem for which Edmonds provided an exact algorithm. For general capacitated trees, Garg, Vazirani, Yannakakis showed the problem is APX-Hard and Chekuri, Mydlarz, Shepherd provided a $4$-approximation. This is essentially the only setting where a constant approximation is known for the general form of \textsc{edp}. We extend their result by giving a constant-factor approximation algorithm for general-form \textsc{edp} in outerplanar graphs. A key component for the algorithm is to find a {\em single-tree} $O(1)$ cut approximator for outerplanar graphs. Previously $O(1)$ cut approximators were only known via distributions on trees and these were based implicitly on the results of Gupta, Newman, Rabinovich and Sinclair for distance tree embeddings combined with results of Anderson and Feige.