论文标题

减少近似近对的新权衡最短路径

New Tradeoffs for Decremental Approximate All-Pairs Shortest Paths

论文作者

Dory, Michal, Forster, Sebastian, Nazari, Yasamin, de Vos, Tijn

论文摘要

我们为减少全对路径(APSP)问题之间的近似和运行时间之间提供了新的权衡。对于具有$ M $边缘和$ n $节点的无向​​图,我们提供了四种新的近似近似APSP算法,两个用于加权的算法,两个用于未加权图。我们的第一个结果是$(2+ε)$ -APSP,带有总更新时间$ \ tilde {o}(m^{1/2} n^{3/2})$(当$ 0 $ 0 <c <1 $时,$ m = n^{1+ c} $)。在我们的工作之前,加权图最快的算法最多,最多为$ 3 $,总$ \ tilde o(mn)$更新时间$(1+ε)$ - apsp [Bernstein,Sicomp 2016]。我们的第二个结果是$(2+ε,w_ {u,v})$ - 带有总更新时间$ \ tilde {o}(nm^{3/4})$的apsp,第二项是$ w_ {u,v} $的附加范围,是$ w_ {u,v} $,是$ u $ u $ $ u $ $ v $的最大路径。 我们的第三个结果是$(2+ε)$ -APSP,用于$ \ tilde o(m^{7/4})$更新时间的未加权图,对于稀疏图($ m = o(n^{8/7})$)是第一个子次数$(2+ε)$ - 近似值。我们未加权图的最后结果是$(1+ε,2(k-1))$ - apsp,对于$ k \ geq 2 $,带有$ \ tilde {o}(n^{2-1/k} m^{1/k} {1/k})$总更新时间(当$ m = n^1+c} $ for constants $ C for noty constants $ C> 0 $)。为了进行比较,在$(1+ε,2)$ - 近似的特殊情况下,这比[Henzinger,Krinninger,Nanongkai,Sicomp 2016]的最先进算法有所改善,总更新时间为$ \ tilde {o} {o}(o}(n^{2.5}))$。我们所有的结果都是随机的,与遗忘的对手作用,并有持续的查询时间。

We provide new tradeoffs between approximation and running time for the decremental all-pairs shortest paths (APSP) problem. For undirected graphs with $m$ edges and $n$ nodes undergoing edge deletions, we provide four new approximate decremental APSP algorithms, two for weighted and two for unweighted graphs. Our first result is $(2+ ε)$-APSP with total update time $\tilde{O}(m^{1/2}n^{3/2})$ (when $m= n^{1+c}$ for any constant $0<c<1$). Prior to our work the fastest algorithm for weighted graphs with approximation at most $3$ had total $\tilde O(mn)$ update time for $(1+ε)$-APSP [Bernstein, SICOMP 2016]. Our second result is $(2+ε, W_{u,v})$-APSP with total update time $\tilde{O}(nm^{3/4})$, where the second term is an additive stretch with respect to $W_{u,v}$, the maximum weight on the shortest path from $u$ to $v$. Our third result is $(2+ ε)$-APSP for unweighted graphs in $\tilde O(m^{7/4})$ update time, which for sparse graphs ($m=o(n^{8/7})$) is the first subquadratic $(2+ε)$-approximation. Our last result for unweighted graphs is $(1+ε, 2(k-1))$-APSP, for $k \geq 2 $, with $\tilde{O}(n^{2-1/k}m^{1/k})$ total update time (when $m=n^{1+c}$ for any constant $c >0$). For comparison, in the special case of $(1+ε, 2)$-approximation, this improves over the state-of-the-art algorithm by [Henzinger, Krinninger, Nanongkai, SICOMP 2016] with total update time of $\tilde{O}(n^{2.5})$. All of our results are randomized, work against an oblivious adversary, and have constant query time.

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