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北美退伍军人节(Veterans Day),12 日无更新
arXiv 1706.09339cs.DScs.CCcs.DM
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稀疏图上连通支配集的有损核

Lossy Kernels for Connected Dominating Set on Sparse Graphs

Eduard Eiben, Mithilesh Kumar, Amer E. Mouawad, Fahad Panolan, Sebastian Siebertz

摘要:

对于$α> 1$,$α$近似(双)内核是一种多项式时间算法,其将问题$\mathcal{Q}$的实例$(I, k)$作为输入,并输出实例$(I',k')$(问题$\mathcal{Q}'$的)由$k$的函数限定的大小,使得对于每个$c\geq 1$,新实例的$c$近似解可以在多项式时间内转换成原始实例的$(c\cdotα)$近似解。这种有损核化的框架是最近引入的Lokshtanov等人。我们研究了连接支配集(及其距离- $r$变体)参数化的解决方案的大小稀疏图类,如bicycle自由图,类的有界扩展,无处密集类。我们证明了,对于每个$α>1$,连接支配集承认多项式大小的$α$ -近似(双)的所有上述类的核心。我们的结果是在鲜明的对比,核化的复杂性连接支配集,这是已知的不承认一个多项式核,即使在$2$ -退化的图形和图形的有界扩展,除非$\textsf{NP} \subseteq \textsf{coNP/poly}$。我们通过下面的条件下界来补充我们的结果。我们证明,如果一个类$\mathcal{C}$是在某处密集和封闭下采取子图,然后对于$r\in\mathbb{N}$的某些值不可能存在一个$α$ -近似双内核的(连接)距离- $r$支配集问题的$\mathcal{C}$的任何$α>1$(假设间隙指数时间假设)。

英文摘要:

For $α> 1$, an $α$-approximate (bi-)kernel is a polynomial-time algorithm that takes as input an instance $(I, k)$ of a problem $\mathcal{Q}$ and outputs an instance $(I',k')$ (of a problem $\mathcal{Q}'$) of size bounded by a function of $k$ such that, for every $c\geq 1$, a $c$-approximate solution for the new instance can be turned into a $(c\cdotα)$-approximate solution of the original instance in polynomial time. This framework of lossy kernelization was recently introduced by Lokshtanov et al. We study Connected Dominating Set (and its distance-$r$ variant) parameterized by solution size on sparse graph classes like biclique-free graphs, classes of bounded expansion, and nowhere dense classes. We prove that for every $α>1$, Connected Dominating Set admits a polynomial-size $α$-approximate (bi-)kernel on all the aforementioned classes. Our results are in sharp contrast to the kernelization complexity of Connected Dominating Set, which is known to not admit a polynomial kernel even on $2$-degenerate graphs and graphs of bounded expansion, unless $\textsf{NP} \subseteq \textsf{coNP/poly}$. We complement our results by the following conditional lower bound. We show that if a class $\mathcal{C}$ is somewhere dense and closed under taking subgraphs, then for some value of $r\in\mathbb{N}$ there cannot exist an $α$-approximate bi-kernel for the (Connected) Distance-$r$ Dominating Set problem on $\mathcal{C}$ for any $α>1$ (assuming the Gap Exponential Time Hypothesis).

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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