论文标题

关于更新和查询一键

On Updating and Querying Submatrices

论文作者

Yang, Jason, Wan, Jun

论文摘要

在本文中,我们研究了$ d $维度的更新问题问题。假设在最低矩阵乘法以及接近下限的算法上,我们提供了更新和查询运行时间的下限。给定$ d $ - 维矩阵,\ textit {update}在给定的子序列中将每个元素从$ x $更改为$ x $ to $ x \ bigtriangledown v $,其中$ v $是给定常数。 A \ textIt {query}返回给定subbatrix中所有元素的$ \ bigtriangleup $。我们研究了$ \ bigtriangledown $和$ \ bigtriangleup $的案例,既是可交换的又是关联二进制运营商。当$ d = 1 $时,可以通过使用带有懒惰的繁殖的细分树来在许多$(\ bigtriangledown,\ bigtriangleup)$中以$ o(\ log n)$最差时间进行更新和查询。但是,当$ d \ ge 2 $时,通常无法推广类似的技术。我们表明,如果无法以$ o(n^{3- \ varepsilon})$计算任何$ \ varepsilon> 0 $的时间(\ bigtriangledown,\ bigtriangleup)=(+bigtriangleup)=(+bigtriangleup)=(+bigtriangleup)=(+bigtriangleup)=(+bigtriangleup)=(+bigtriangleup)=(+bigtriangleup)=(+bigtriangleup)=(+bigtriangleup)=(+bigtriangleup)=(+bigtriangleup)=( $ o(n^{1- \ varepsilon})$时间对于任何常数$ \ varepsilon> 0 $,或者预处理无法在多项式时间内运行。最后,我们展示了一种特殊情况,可以将懒惰的传播以$ d \ ge 2 $概括,并且更新和查询可以在$ o(\ log^d n)$最差时间的时间内运行。我们提出了一种符合此运行时间的算法,并且比以前作品的类似算法更简单。

In this paper, we study the $d$-dimensional update-query problem. We provide lower bounds on update and query running times, assuming a long-standing conjecture on min-plus matrix multiplication, as well as algorithms that are close to the lower bounds. Given a $d$-dimensional matrix, an \textit{update} changes each element in a given submatrix from $x$ to $x\bigtriangledown v$, where $v$ is a given constant. A \textit{query} returns the $\bigtriangleup$ of all elements in a given submatrix. We study the cases where $\bigtriangledown$ and $\bigtriangleup$ are both commutative and associative binary operators. When $d = 1$, updates and queries can be performed in $O(\log N)$ worst-case time for many $(\bigtriangledown,\bigtriangleup)$ by using a segment tree with lazy propagation. However, when $d\ge 2$, similar techniques usually cannot be generalized. We show that if min-plus matrix multiplication cannot be computed in $O(N^{3-\varepsilon})$ time for any $\varepsilon>0$ (which is widely believed to be the case), then for $(\bigtriangledown,\bigtriangleup)=(+,\min)$, either updates or queries cannot both run in $O(N^{1-\varepsilon})$ time for any constant $\varepsilon>0$, or preprocessing cannot run in polynomial time. Finally, we show a special case where lazy propagation can be generalized for $d\ge 2$ and where updates and queries can run in $O(\log^d N)$ worst-case time. We present an algorithm that meets this running time and is simpler than similar algorithms of previous works.

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