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arXiv 1901.01665cs.DCcs.DSmath.PR
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有限内存节点共识的通信代价

Communication cost of consensus for nodes with limited memory

Giulia Fanti, Nina Holden, Yuval Peres, Gireeja Ranade

摘要:

受区块链和传感器网络应用的启发,我们考虑了一个$n$节点试图在其多数位上达成共识的模型。每个节点$i$在时间0被分配一个位,并且是具有存储器的$m$位的有限自动机(即,$2^m$状态)和泊松时钟。当$i$的时钟振铃时,$i$可以选择通信,然后匹配到统一选择的节点$j$。节点$j$和$i$可以基于另一个节点的状态来更新它们的状态。以前的工作集中在最小化达成共识的时间和错误的概率,而我们的目标是最小化通信的数量。我们表明,当$m>3 \log\log\log(n)$,共识可以达到线性通信成本,但这是不可能的,如果$m<\log\log\log(n)$。我们还研究了一个同步的模型,其中我们的上限和下限$m$实现线性通信成本分别为$2\log\log\log(n)$和$\log\log\log(n)$。一个关键步骤是区分节点何时可以意识到知道多数位并停止通信。我们表明,这是不可能的,如果他们的记忆太低。

英文摘要:

Motivated by applications in blockchains and sensor networks, we consider a model of $n$ nodes trying to reach consensus on their majority bit. Each node $i$ is assigned a bit at time zero, and is a finite automaton with $m$ bits of memory (i.e., $2^m$ states) and a Poisson clock. When the clock of $i$ rings, $i$ can choose to communicate, and is then matched to a uniformly chosen node $j$. The nodes $j$ and $i$ may update their states based on the state of the other node. Previous work has focused on minimizing the time to consensus and the probability of error, while our goal is minimizing the number of communications. We show that when $m>3 \log\log\log(n)$, consensus can be reached at linear communication cost, but this is impossible if $m<\log\log\log(n)$. We also study a synchronous variant of the model, where our upper and lower bounds on $m$ for achieving linear communication cost are $2\log\log\log(n)$ and $\log\log\log(n)$, respectively. A key step is to distinguish when nodes can become aware of knowing the majority bit and stop communicating. We show that this is impossible if their memory is too low.

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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