arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 1503.00609math.PRcs.ITcs.SImath.IT
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一般随机块模型中的社区检测:基本极限和有效恢复算法

Community detection in general stochastic block models: fundamental limits and efficient recovery algorithms

Emmanuel Abbe, Colin Sandon

摘要:

随机块模型是两个非重叠对称社区的特殊情况,最近发现了新的相变现象。这特别提出了由阈值驱动的新算法挑战。本文探讨了是否有一个普遍的现象发生在多个社区,而不强加对称性。在一般的随机块模型$\text{SBM}(n,p,Q)$中,$n$顶点被分成大小为$\{p_i\}_{i \in [k]}$的$k$社区,社区中的顶点$i$和$j$以概率$\{Q_{i,j}\}_{i,j \in [k]}$独立连接.本文研究了一般SBM(在常数和对数度制度)的社区的部分和精确恢复,并使用结果的一般性来解决重叠社区。该论文的贡献包括:(i)根据新的发散函数$D_+$的一般SBM中的恢复阈值的明确表征,该新的发散函数推广了Hellinger发散和Bauffff发散,并且向类似于信道编码定理中的KL发散的发散函数提供了操作意义,(ii)开发一种算法,该算法将社区一直恢复到最佳阈值,并在准线性时间内运行,表明精确恢复对于多个社区没有信息理论到计算差距,与4个以上群落的检测结果相反;注意该算法在达到阈值和具有准线性复杂度方面都是最优的,(iii)发展一种有效的算法,在常数度范围内检测社区,并具有明确的准确性界限,当指定信号-信噪比(根据$\diag(p)Q$的光谱定义)趋于无穷大。

英文摘要:

New phase transition phenomena have recently been discovered for the stochastic block model, for the special case of two non-overlapping symmetric communities. This gives raise in particular to new algorithmic challenges driven by the thresholds. This paper investigates whether a general phenomenon takes place for multiple communities, without imposing symmetry. In the general stochastic block model $\text{SBM}(n,p,Q)$, $n$ vertices are split into $k$ communities of relative size $\{p_i\}_{i \in [k]}$, and vertices in community $i$ and $j$ connect independently with probability $\{Q_{i,j}\}_{i,j \in [k]}$. This paper investigates the partial and exact recovery of communities in the general SBM (in the constant and logarithmic degree regimes), and uses the generality of the results to tackle overlapping communities. The contributions of the paper are: (i) an explicit characterization of the recovery threshold in the general SBM in terms of a new divergence function $D_+$, which generalizes the Hellinger and Chernoff divergences, and which provides an operational meaning to a divergence function analog to the KL-divergence in the channel coding theorem, (ii) the development of an algorithm that recovers the communities all the way down to the optimal threshold and runs in quasi-linear time, showing that exact recovery has no information-theoretic to computational gap for multiple communities, in contrast to the conjectures made for detection with more than 4 communities; note that the algorithm is optimal both in terms of achieving the threshold and in having quasi-linear complexity, (iii) the development of an efficient algorithm that detects communities in the constant degree regime with an explicit accuracy bound that can be made arbitrarily close to 1 when a prescribed signal-to-noise ratio (defined in term of the spectrum of $\diag(p)Q$) tends to infinity.

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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