arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 1402.4306stat.MLcs.AIcs.LGstat.ME
收藏

Student-t过程作为高斯过程的替代

Student-t Processes as Alternatives to Gaussian Processes

University of Cambridge(剑桥大学)

Amar Shah, Andrew Gordon Wilson, Zoubin Ghahramani

摘要:

我们调查学生t过程作为替代的高斯过程作为一个非参数先验函数。通过在高斯过程模型的协方差核上先积分一个逆Wishart过程,得到了Student-t过程的边缘似然和预测分布的封闭形式表达式.我们发现令人惊讶的等效性不同层次的高斯过程模型导致学生t过程,并推导出一个新的采样方案的逆Wishart过程,这有助于阐明这些等效性。总体而言,我们表明,学生t过程可以保留高斯过程的吸引人的属性-非参数表示,分析的边缘和预测分布,并通过协方差内核容易模型选择-但具有增强的灵活性,预测协方差,不像高斯过程,明确地依赖于训练观测值。我们经验验证,学生t过程是特别有用的情况下,有变化的协方差结构,或在应用程序,如贝叶斯优化,准确的预测协方差是至关重要的良好的性能。这些优点与高斯过程相比没有额外的计算成本。

英文摘要:

We investigate the Student-t process as an alternative to the Gaussian process as a nonparametric prior over functions. We derive closed form expressions for the marginal likelihood and predictive distribution of a Student-t process, by integrating away an inverse Wishart process prior over the covariance kernel of a Gaussian process model. We show surprising equivalences between different hierarchical Gaussian process models leading to Student-t processes, and derive a new sampling scheme for the inverse Wishart process, which helps elucidate these equivalences. Overall, we show that a Student-t process can retain the attractive properties of a Gaussian process -- a nonparametric representation, analytic marginal and predictive distributions, and easy model selection through covariance kernels -- but has enhanced flexibility, and predictive covariances that, unlike a Gaussian process, explicitly depend on the values of training observations. We verify empirically that a Student-t process is especially useful in situations where there are changes in covariance structure, or in applications like Bayesian optimization, where accurate predictive covariances are critical for good performance. These advantages come at no additional computational cost over Gaussian processes.

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。

↑