0


预期传递的扰乱性修正

Perturbative Corrections to Expectation Consistent Approximate Inference
课程网址: http://videolectures.net/abi07_opper_pce/  
主讲教师: Manfred Opper
开课单位: 柏林工业大学
开课时间: 2007-12-31
课程语种: 英语
中文简介:
近似推理的算法通常不保证近似的质量。然而,我们经常发现这样的算法在计算后验矩时,与耗时(和极限精确)的MC模拟或精确枚举相比,执行得非常好。一个突出的例子是期望传播(EP)算法在高斯过程分类中的应用。我们能理解什么时候以及为什么我们可以相信这些近似的结果吗?或者,如果不能,我们怎样才能得到系统的改进?在这次讲座中,我们利用期望一致性(EC)[1]的思想重新推导了EP的不动点条件,并明确考虑了近似中忽略的项。我们将展示如何为这个修正导出一个正式的(渐近的)幂级数展开式,并计算它的前导项。我们将举例说明GP分类的方法,以及关于伊辛变量网络的方法。期望一致近似推理,Manfred Opper和Ole Winther, JMLR 6,2177 - 2204(2005)。
课程简介: Algorithms for approximate inference usually come without any guarantee for the quality of the approximation. Nevertheless, we often find cases where such algorithms perform extremely well on the computation of posterior moments when compared to time consuming (and in the limit exact) MC simulations or exact enumerations. \\ A prominent example is the Expectation Propagation (EP) algorithm when applied to Gaussian process classification. Can we understand when and why we can trust the approximate results or, if not, how we could obtain systematic improvements? \\ In this talk, we rederive the fixed point conditions of EP using the ideas of expectation consistency (EC) [1] and explicitly consider the terms neglected in the approximation. We will show how one can derive a formal (asymptotic) power series expansion for this correction and compute its leading terms. We will illustrate the approach for the case of GP classification and for networks of Ising variables. \\ [1] Expectation Consistent Approximate Inference, Manfred Opper and Ole Winther, JMLR 6, 2177 - 2204 (2005).
关 键 词: 预期传递; 扰乱性; 修正
课程来源: 视频讲座网
最后编审: 2019-11-02:lxf
阅读次数: 29