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GMRFs的留言和非线性优化传递算法

Message-Passing Algorithms for GMRFs and Non-Linear Optimization
课程网址: http://videolectures.net/abi07_johnson_mpa/  
主讲教师: Jason K. Johnson
开课单位: 麻省理工学院
开课时间: 2008-02-01
课程语种: 英语
中文简介:
摘要综述了高斯图形模型中各种迭代推理和估计方法,即高斯-马尔可夫随机场(GMRFs),并讨论了如何将这些方法应用于包含图形结构目标函数的非线性优化问题。特别地,我们回顾了高斯信念传播(GaBP)的“走合”解释,并考虑了一种新的总是收敛于最优估计的稳定形式GaBP。在另一个方向,我们讨论了一种适用于GMRFs的迭代拉格朗日松弛方法,该方法分解为图簇上定义的凸二次势函数的和。然后我们考虑如何将这些方法用于求解具有光滑势函数的更一般的MRFs类。例如,如果势能函数是凸的,那么利用高斯推理来有效地实现牛顿方法,从而得到最优解是很直接的。在非凸MRFs中,仍然可以使用Levenberg-Marquardt的方法获得近似解。在时间允许的情况下,我们还可以考虑具有非光滑势函数的磁流变液半二次优化方法。在所有这些方法中,该问题近似为一系列凸二次型问题,每个凸二次型问题都可以使用高斯推理技术以分布式方式解决。
课程简介: We review a variety of iterative methods for inference and estimation in Gaussian graphical models, also known as Gauss-Markov random fields (GMRFs), and consider how to adapt these methods to non-linear optimization problems involving graph-structured objective functions. Specifically, we review the ''walk-sum'' interpretation of Gaussian belief propagation (GaBP) and consider a novel stable form of GaBP which always converges to the optimal estimate. In another direction, we discuss an iterative Lagrangian relaxation method applicable for GMRFs which decompose as a sum of convex quadratic potential functions defined on cliques of the graph. We then consider how such methods can be adapted to solve more general classes of MRFs with smooth potential functions. For instance, if the potential functions are convex, it is straight-forward to use Gaussian inference to efficiently implement Newton's method leading to the optimal solution. In non-convex MRFs, it is still possible to obtain approximate solutions using the method of Levenberg-Marquardt. As time permits, we may also consider the half-quadratic optimization approach for MRFs having non-smooth potential functions. In all of these approaches, the problem is approximated by a sequence of convex quadratic problems each of which can be solved in a distributed fashion using Gaussian inference techniques.
关 键 词: GMRFs; 非线性优化传递; 算法
课程来源: 视频讲座网
最后编审: 2020-06-10:王勇彬(课程编辑志愿者)
阅读次数: 98