arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 1406.7445cs.LG
收藏

基于对比特征的条件随机场结构学习算法

Contrastive Feature Induction for Efficient Structure Learning of Conditional Random Fields

Carnegie Mellon University(卡内基梅隆大学)

Ni Lao, Jun Zhu

摘要:

条件随机场的结构学习可以转化为一个L1正则化优化问题。为了避免在完全链接的模型上进行优化,基于增益或基于梯度的特征选择方法从一个空模型开始,并逐渐向其添加排名靠前的特征。然而,对于统计关系学习等高维问题,这些增量方法的训练时间可能会受到评估大量候选特征的增益或梯度的成本的影响。在这项研究中,我们提出了一种快速的特征评估算法,称为对比特征归纳(CFI),它只评估一个子集的功能,涉及高信号(偏离均值)和高误差(残差)的变量。我们证明了候选特征的梯度可以单独表示为信号和误差的函数,并且CFI是基于梯度的评估方法的有效近似。在合成和真实数据集上的实验表明,与最先进的结构学习方法(如对所有特征的完全优化和嫁接)相比,CFI在成对CRF上的学习速度和准确性具有竞争力。

英文摘要:

Structure learning of Conditional Random Fields (CRFs) can be cast into an L1-regularized optimization problem. To avoid optimizing over a fully linked model, gain-based or gradient-based feature selection methods start from an empty model and incrementally add top ranked features to it. However, for high-dimensional problems like statistical relational learning, training time of these incremental methods can be dominated by the cost of evaluating the gain or gradient of a large collection of candidate features. In this study we propose a fast feature evaluation algorithm called Contrastive Feature Induction (CFI), which only evaluates a subset of features that involve both variables with high signals (deviation from mean) and variables with high errors (residue). We prove that the gradient of candidate features can be represented solely as a function of signals and errors, and that CFI is an efficient approximation of gradient-based evaluation methods. Experiments on synthetic and real data sets show competitive learning speed and accuracy of CFI on pairwise CRFs, compared to state-of-the-art structure learning methods such as full optimization over all features, and Grafting.

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。

↑