论文标题

修补部分解决方案,几乎没有更改

Mending Partial Solutions with Few Changes

论文作者

Melnyk, Darya, Suomela, Jukka, Villani, Neven

论文摘要

在本文中,我们研究了修补的概念,即给出了图形问题的部分解决方案,我们研究了将其变成适当的解决方案需要多少精力。例如,如果我们具有部分颜色的图形,那么将其变成适当的颜色有多困难? 在先前的工作(Sirocco 2022)中,从修补半径的角度进行了形式化并研究了这个问题:如果我们需要修补一个孔,我们需要多远修改解决方案?在这项工作中,我们研究了修补量的互补概念:需要修改多少个节点以修补一个孔? We focus on the case of locally checkable labeling problems (LCLs) in trees, and show that already in this setting there are two infinite hierarchies of problems: for infinitely many values $0 < α\le 1$, there is an LCL problem with mending volume $Θ(n^α)$, and for infinitely many values $k \ge 1$, there is an LCL problem with mending volume $Θ(\log^k n)$.因此,树木上LCL问题的修复性是一个比仅基于修补半径的预期要高得多的问题。 We define three variants of the theme: (1) existential mending volume, i.e., how many nodes need to be modified, (2) expected mending volume, i.e., how many nodes we need to explore to find a patch if we use randomness, and (3) deterministic mending volume, i.e., how many nodes we need to explore if we use a deterministic algorithm.我们表明,这三个概念彼此不同,我们分析了相应模型的LCL问题复杂性的景观。

In this paper, we study the notion of mending, i.e. given a partial solution to a graph problem, we investigate how much effort is needed to turn it into a proper solution. For example, if we have a partial coloring of a graph, how hard is it to turn it into a proper coloring? In prior work (SIROCCO 2022), this question was formalized and studied from the perspective of mending radius: if there is a hole that we need to patch, how far do we need to modify the solution? In this work, we investigate a complementary notion of mending volume: how many nodes need to be modified to patch a hole? We focus on the case of locally checkable labeling problems (LCLs) in trees, and show that already in this setting there are two infinite hierarchies of problems: for infinitely many values $0 < α\le 1$, there is an LCL problem with mending volume $Θ(n^α)$, and for infinitely many values $k \ge 1$, there is an LCL problem with mending volume $Θ(\log^k n)$. Hence the mendability of LCL problems on trees is a much more fine-grained question than what one would expect based on the mending radius alone. We define three variants of the theme: (1) existential mending volume, i.e., how many nodes need to be modified, (2) expected mending volume, i.e., how many nodes we need to explore to find a patch if we use randomness, and (3) deterministic mending volume, i.e., how many nodes we need to explore if we use a deterministic algorithm. We show that all three notions are distinct from each other, and we analyze the landscape of the complexities of LCL problems for the respective models.

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