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arXiv 1910.01552cs.DSmath.PR
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数学Lovasz局部引理的推广

Extensions of the Algorithmic Lovasz Local Lemma

Vladimir Kolmogorov

摘要:

我们考虑Achlioptas-Iliopoulos-Kolmogorov [2]和Achlioptas-Iliopoulos-Sinclair [3]最近提出的算法Lovasz局部引理。这些论文分析了一个随机游走算法,用于寻找避免不希望的“坏事件”(或“缺陷”)的对象,并证明在某些条件下,该算法可以保证快速找到一个“完美”的对象。我们表明,这些文件中提出的条件是不可比较的,并介绍了一个新的家庭的条件,包括那些在[2,3]作为特殊情况。我们还考虑了[3]中在稀疏k-SAT公式的背景下出现的另一个条件。这个条件对问题的每个变量施加了约束,而传统的LLL公式对每个子句施加了约束。Achlioptas等人通过减少到不同的条件,然后应用单子句回溯算法来处理基于变量的条件。我们提出了一个新的条件,直接捕获[3]中考虑的稀疏k-SAT应用,并允许使用标准的局部搜索算法(提供了重要的优势,如并行化)。最后,我们从[20]中扩展了我们以前的“交换性”概念,并使用我们开发的一些新工具证明了交换性的几个含义。特别地,我们简化了Iliopoulos [16]关于近似LLL分布的结果。

英文摘要:

We consider recent formulations of the algorithmic Lovasz Local Lemma by Achlioptas-Iliopoulos-Kolmogorov [2] and by Achlioptas-Iliopoulos-Sinclair [3]. These papers analyze a random walk algorithm for finding objects that avoid undesired "bad events" (or "flaws"), and prove that under certain conditions the algorithm is guaranteed to find a "flawless" object quickly. We show that conditions proposed in these papers are incomparable, and introduce a new family of conditions that includes those in [2, 3] as special cases. We also consider another condition that appeared in [3] in the context of sparse k-SAT formulas. This condition imposes a constraint for each variable of the problem, whereas traditional LLL formulations impose a constraint for each clause. Achlioptas et al. handled the variable-based condition via a reduction to a different condition and then applying a single-clause backtracking algorithm. We propose a new condition that directly captures the sparse k-SAT application considered in [3], and allows the use of the standard local search algorithm (which offers important advantages such as parallelization). Finally, we extend our previous notion of "commutativity" from [20] and prove several implications of commutativity using some new tools that we develop. In particular, we simplify the result of Iliopoulos [16] about approximating the LLL distribution.

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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