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arXiv 1206.3252cs.LGstat.ML
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基于无向贝叶斯转移分层的凸点估计

Convex Point Estimation using Undirected Bayesian Transfer Hierarchies

Stanford University(斯坦福大学)

Gal Elidan, Ben Packer, Geremy Heitz, Daphne Koller

摘要:

当相关的学习任务被自然地安排在一个层次结构中时,一个有吸引力的处理实例稀缺的方法是使用层次贝叶斯框架的迁移学习。由于完全贝叶斯计算可能是困难的,并且计算要求很高,因此通常希望使用有助于(相对)有效预测的后验点估计。然而,分层贝叶斯框架并不总是自然地适用于这一最大后验目标。在这项工作中,我们提出了一个无向重构的分层贝叶斯依赖于先验的形式相似性措施。我们引入的概念,这些相似性措施的组件上的“转移度”的权重,并展示了它们如何可以自动学习的联合概率框架内。重要的是,我们的重新制定的结果在许多学习问题的凸目标,从而促进最佳后验点估计使用标准的优化技术。此外,我们不再需要适当的先验知识,允许灵活和直接的规范的联合分布在传输层次。我们表明,我们的框架是有效的学习模型的一部分,传输层次结构的两个现实生活中的任务:对象形状建模使用高斯密度估计和文档分类。

英文摘要:

When related learning tasks are naturally arranged in a hierarchy, an appealing approach for coping with scarcity of instances is that of transfer learning using a hierarchical Bayes framework. As fully Bayesian computations can be difficult and computationally demanding, it is often desirable to use posterior point estimates that facilitate (relatively) efficient prediction. However, the hierarchical Bayes framework does not always lend itself naturally to this maximum aposteriori goal. In this work we propose an undirected reformulation of hierarchical Bayes that relies on priors in the form of similarity measures. We introduce the notion of "degree of transfer" weights on components of these similarity measures, and show how they can be automatically learned within a joint probabilistic framework. Importantly, our reformulation results in a convex objective for many learning problems, thus facilitating optimal posterior point estimation using standard optimization techniques. In addition, we no longer require proper priors, allowing for flexible and straightforward specification of joint distributions over transfer hierarchies. We show that our framework is effective for learning models that are part of transfer hierarchies for two real-life tasks: object shape modeling using Gaussian density estimation and document classification.

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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