论文标题

在更可信的假设下,三角问题的硬度:从真正的APSP,Real 3sum和OV中减少

Hardness for Triangle Problems under Even More Believable Hypotheses: Reductions from Real APSP, Real 3SUM, and OV

论文作者

Chan, Timothy M., Williams, Virginia Vassilevska, Xu, Yinzhan

论文摘要

$ 3 $总的假设,APSP假设和Seth是细粒复杂性中的三个主要假设。到目前为止,在该区域内,前两个假设主要是关于“ RAM”一词计算模型中的整数输入。 “真实的APSP”和“ Real $ 3 $ sum”假设认为,在合理版本的真实RAM模型中,APSP和$ 3 $ sum假设对真实价​​值的输入所保留,这比整数更可信。 在一个非常可信的假设下,整数$ 3 $总假设中的至少一个,整数APSP假设或Seth是正确的,Abboud,Vassilevska W.和Yu [Stoc 2015]表明,一个称为Triangle Collection的问题需要$ n^{3-o(1)} $ N $ n $ -node-node-node-node-node-node-node。 我们的主要结果是在更令人难以置信的假设下,在三角形的三角形三角收集中进行了轻微的概括,即至少有一个真正的$ 3 $总和之一,真正的APSP和OV假设是正确的。结合先前减少的轻微修改,我们获得了(静态的)ST-MAX流量问题和动态最大流量等问题的多项式条件下限,现在在新的较弱的假设下。 我们的主要结果是基于以下两条减少行。 *真正的APSP和REAL $ 3 $总和硬度稀疏三角问题。事先减少仅来自这些问题的整数变体。 *用于布尔矩阵乘法问题的变体的真实APSP和OV硬度。 在此过程中,我们表明三角集合等同于问题的更简单的限制版本,简化了先前的工作。我们的技术还具有其他有趣的含义,例如,基于实际$ 3 $总假设的整数全数$ 3 $总和的超级线性下限,以及基于OV假设的弦匹配问题的紧密下限。

The $3$SUM hypothesis, the APSP hypothesis and SETH are the three main hypotheses in fine-grained complexity. So far, within the area, the first two hypotheses have mainly been about integer inputs in the Word RAM model of computation. The "Real APSP" and "Real $3$SUM" hypotheses, which assert that the APSP and $3$SUM hypotheses hold for real-valued inputs in a reasonable version of the Real RAM model, are even more believable than their integer counterparts. Under the very believable hypothesis that at least one of the Integer $3$SUM hypothesis, Integer APSP hypothesis or SETH is true, Abboud, Vassilevska W. and Yu [STOC 2015] showed that a problem called Triangle Collection requires $n^{3-o(1)}$ time on an $n$-node graph. Our main result is a nontrivial lower bound for a slight generalization of Triangle Collection, called All-Color-Pairs Triangle Collection, under the even more believable hypothesis that at least one of the Real $3$SUM, the Real APSP, and the OV hypotheses is true. Combined with slight modifications of prior reductions, we obtain polynomial conditional lower bounds for problems such as the (static) ST-Max Flow problem and dynamic Max Flow, now under the new weaker hypothesis. Our main result is built on the following two lines of reductions. * Real APSP and Real $3$SUM hardness for the All-Edges Sparse Triangle problem. Prior reductions only worked from the integer variants of these problems. * Real APSP and OV hardness for a variant of the Boolean Matrix Multiplication problem. Along the way we show that Triangle Collection is equivalent to a simpler restricted version of the problem, simplifying prior work. Our techniques also have other interesting implications, such as a super-linear lower bound of Integer All-Numbers $3$SUM based on the Real $3$SUM hypothesis, and a tight lower bound for a string matching problem based on the OV hypothesis.

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