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自然语言处理中推理的对偶分解

Dual decomposition for inference in natural language processing
课程网址: http://videolectures.net/nipsworkshops2010_koo_ddi/  
主讲教师: Terry Koo
开课单位: 麻省理工学院
开课时间: 2011-01-13
课程语种: 英语
中文简介:
利用双重分解或拉格朗日松弛等方法,在复杂问题中利用结构的方法进行组合优化已有很长的历史。这些方法利用了复杂推理问题通常可以分解为有效可解的子问题的观察。在本讲中我将描述基于对偶分解的NLP推理算法研究。我将描述关于twoproblems的工作:1)非投影依赖解析,其中除了最简单的模型之外,所有参考问题都是NP难的。 2)涉及两个或多个动态编程问题的“交叉点”的问题。这些问题在多项式时间内是可以解决的,但在实践中,相交的动态程序太大而不实用。算法简单而有效,建立在标准组合算法(例如,动态编程,最小生成树)上作为神谕;它们可以解决原始问题的线性规划松弛;而且凭经验他们经常会导致对原始问题的精确解决方案。这项工作涉及最近的方法,即在马尔可夫随机场中使用双重分解作为信任传播的替代方法。这是与TommiJaakkola,Terry Koo,Sasha Rush和David Sontag的联合工作。
课程简介: There has been a long history in combinatorial optimization of methods that exploit structure in complex problems, using methods such as dual decomposition or Lagrangian relaxation. These methods leverage the observation that complex inference problems can often be decomposed into efficiently solvable subproblems. In this talk I’ll describe work on inference algorithms for NLP based on dual decomposition. I’ll describe work on two problems: 1) Non-projective dependency parsing, where the inference problem is NP-hard for all but the simplest models. 2) Problems that involve ‘‘intersections’’ of two or more dynamic programming problems. These problems are solvable in polynomial time, but in practice the intersected dynamic programs are far too large to be practical. The algorithms are simple and efficient, building on standard combinatorial algorithms (e.g., dynamic programming, minimum spanning tree) as oracles; they provably solve a linear programming relaxation of the original problem; and empirically they very often lead to an exact solution to the original problem. The work is related to recent methods that use dual decomposition as an alternative to belief propagation for inference in Markov random fields. This is joint work with Tommi Jaakkola, Terry Koo, Sasha Rush, and David Sontag.
关 键 词: 双重分解; 拉格朗日松弛; NLP推理算法
课程来源: 视频讲座网
最后编审: 2019-09-07:lxf
阅读次数: 78