arXivDaily arXiv每日学术速递 周一至周五更新
arXiv周末暂无论文更新,休息一下吧,周末愉快~~
arXiv 2011.03291cs.DS
收藏

所有对Mincuts的灵敏度神谕

Sensitivity Oracles for All-Pairs Mincuts

Surender Baswana, Abhyuday Pandey

摘要:

设$G=(V,E)$是$n$顶点和$m$边上的无向无权图.我们解决了$G$中所有对mincut的敏感性预言问题,定义如下。建立一个紧凑的数据结构,在接收到任何一对顶点$s,t\in V$和任何边的失败(或插入)作为查询时,可以有效地报告失败(或插入)后$s$和$t$之间的mincut。据我们所知,这个问题不存在数据结构,需要$o(mn)$空间和非平凡的查询时间。我们提出以下结果。- 我们的第一个数据结构占用${\cal O}(n^2)$空间,并保证${\cal O}(1)$查询时间,以报告任何边失败(或插入)时产生的$(s,t)$ -mincut的值。此外,可以在最坏情况下最优的${\cal O}(n)$时间内报告定义更新后所得$(s,t)$ -mincut的顶点集。- 我们的第二种数据结构以增加查询时间为代价优化了空间。它占用${\cal O}(m)$空间--这也是$G$占用的空间。查询时间为${\cal O}(\min(m,n c_{s,t}))$,其中$c_{s,t}$是$G$中$s$和$t$之间的mincut值。与从头开始计算$(s,t)$ -mincut的最佳已知确定性算法相比,该查询时间快了$Ω(\min(m^{1/3},\sqrt{n}))$倍。- 如果我们只想知道一条边的失败(或插入)是否会改变$(s,t)$ -mincut的值,我们可以将${\cal O}(n^2)$空间数据结构均匀地分布在$n$顶点之间。对于任何失败的(或插入的)边,我们只需要存储在其端点的数据结构来确定$(s,t)$ -mincut的值是否针对任何$s,t \in V$发生了变化。

英文摘要:

Let $G=(V,E)$ be an undirected unweighted graph on $n$ vertices and $m$ edges. We address the problem of sensitivity oracle for all-pairs mincuts in $G$ defined as follows. Build a compact data structure that, on receiving any pair of vertices $s,t\in V$ and failure (or insertion) of any edge as query, can efficiently report the mincut between $s$ and $t$ after the failure (or the insertion). To the best of our knowledge, there exists no data structure for this problem which takes $o(mn)$ space and a non-trivial query time. We present the following results. - Our first data structure occupies ${\cal O}(n^2)$ space and guarantees ${\cal O}(1)$ query time to report the value of resulting $(s,t)$-mincut upon failure (or insertion) of any edge. Moreover, the set of vertices defining a resulting $(s,t)$-mincut after the update can be reported in ${\cal O}(n)$ time which is worst-case optimal. - Our second data structure optimizes space at the expense of increased query time. It takes ${\cal O}(m)$ space -- which is also the space taken by $G$. The query time is ${\cal O}(\min(m,n c_{s,t}))$ where $c_{s,t}$ is the value of the mincut between $s$ and $t$ in $G$. This query time is faster by a factor of $Ω(\min(m^{1/3},\sqrt{n}))$ compared to the best known deterministic algorithm to compute a $(s,t)$-mincut from scratch. - If we are only interested in knowing if failure (or insertion) of an edge changes the value of $(s,t)$-mincut, we can distribute our ${\cal O}(n^2)$ space data structure evenly among $n$ vertices. For any failed (or inserted) edge we only require the data structures stored at its endpoints to determine if the value of $(s,t)$-mincut has changed for any $s,t \in V$.

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。

↑