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arXiv 1101.0673stat.ML
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时间序列的自回归核

Autoregressive Kernels For Time Series

Marco Cuturi, Arnaud Doucet

摘要:

在这项工作中,我们提出了一个新的家庭的内核可变长度的时间序列。我们的工作建立在多元随机过程的向量自回归(VAR)模型的基础上:给定一个多元时间序列x,我们考虑VAR模型中不同参数θ的似然函数p θ(x)作为描述x的特征。为了比较两个时间序列x和x ',我们形成它们的特征p_θ(x)p_θ(x')的乘积,该乘积使用矩阵正态-逆Wishart先验对t θ进行积分。在其他属性中,当时间序列的维度d比所考虑的时间序列x和x '的长度大得多时,可以容易地计算该核。它也可以推广到在任意状态空间中取值的时间序列,只要状态空间本身被赋予一个核κ。在这种情况下,x和x'之间的核是由κ在x和x'中枚举的观测和观测的连续性上产生的格拉姆矩阵的函数。我们描述了一个计算效率的实现,使用低秩矩阵分解技术的推广。这些内核相比,其他已知的内核使用一组基准分类任务进行支持向量机。

英文摘要:

We propose in this work a new family of kernels for variable-length time series. Our work builds upon the vector autoregressive (VAR) model for multivariate stochastic processes: given a multivariate time series x, we consider the likelihood function p_θ(x) of different parameters θin the VAR model as features to describe x. To compare two time series x and x', we form the product of their features p_θ(x) p_θ(x') which is integrated out w.r.t θusing a matrix normal-inverse Wishart prior. Among other properties, this kernel can be easily computed when the dimension d of the time series is much larger than the lengths of the considered time series x and x'. It can also be generalized to time series taking values in arbitrary state spaces, as long as the state space itself is endowed with a kernel κ. In that case, the kernel between x and x' is a a function of the Gram matrices produced by κon observations and subsequences of observations enumerated in x and x'. We describe a computationally efficient implementation of this generalization that uses low-rank matrix factorization techniques. These kernels are compared to other known kernels using a set of benchmark classification tasks carried out with support vector machines.

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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