arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 1707.05065math.OCcs.DS
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次模函数最小化的几何重标度算法

Geometric Rescaling Algorithms for Submodular Function Minimization

Daniel Dadush, László A. Végh, Giacomo Zambelli

摘要:

提出了一类新的次模函数最小化的多项式时间算法,并给出了得到强多项式次模函数最小化算法的统一框架。我们的算法是基于简单的迭代方法的最小范数问题,如条件梯度和Fujishige-Wolfe算法。我们展示了两种技术,把简单的迭代方法到多项式时间算法。首先,我们适应的几何缩放技术,这是最近在线性规划中得到关注,SFM和得到一个弱多项式界$O(({n}^4\cdot \textrm{EO} + {n}^5)\log ({n} L))$。其次,我们展示了一个通用的组合黑箱方法,把$\varepsilon L$ -近似SFM神谕到强多项式精确SFM算法。这个框架可以应用到广泛的组合和连续算法,包括伪多项式的。特别地,我们可以通过重复应用条件梯度或Fujishige-Wolfe算法来获得强多项式算法。结合几何缩放技术,黑盒方法提供了一个$O(({n}^5\cdot \textrm{EO} +{n}^6)\log^2{n})$算法。最后,我们表明,我们在本文中开发的技术之一,也可以结合割平面法李,Sidford和黄\cite{LSW},产生一个简化的变种,他们的$O(n^3 \log^2 n \cdot \textrm{EO} + n^4\log^{O(1)} n)$算法。

英文摘要:

We present a new class of polynomial-time algorithms for submodular function minimization (SFM), as well as a unified framework to obtain strongly polynomial SFM algorithms. Our algorithms are based on simple iterative methods for the minimum-norm problem, such as the conditional gradient and Fujishige-Wolfe algorithms. We exhibit two techniques to turn simple iterative methods into polynomial-time algorithms. Firstly, we adapt the geometric rescaling technique, which has recently gained attention in linear programming, to SFM and obtain a weakly polynomial bound $O(({n}^4\cdot \textrm{EO} + {n}^5)\log ({n} L))$. Secondly, we exhibit a general combinatorial black-box approach to turn $\varepsilon L$-approximate SFM oracles into strongly polynomial exact SFM algorithms. This framework can be applied to a wide range of combinatorial and continuous algorithms, including pseudo-polynomial ones. In particular, we can obtain strongly polynomial algorithms by a repeated application of the conditional gradient or of the Fujishige-Wolfe algorithm. Combined with the geometric rescaling technique, the black-box approach provides an $O(({n}^5\cdot \textrm{EO} +{n}^6)\log^2{n})$ algorithm. Finally, we show that one of the techniques we develop in the paper can also be combined with the cutting-plane method of Lee, Sidford, and Wong \cite{LSW}, yielding a simplified variant of their $O(n^3 \log^2 n \cdot \textrm{EO} + n^4\log^{O(1)} n)$ algorithm.

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