向量值正则化最小二乘算法的最优 Sobolev 范数速率研究
Towards Optimal Sobolev Norm Rates for the Vector-Valued Regularized Least-Squares Algorithm
AI总结:
本文研究无穷维向量值核岭回归,利用向量值插值空间的张量积构造刻画光滑性,在错误设定下建立与输出维数无关且多数情形最优的连续范数速率。
摘要:
我们给出了无穷维向量值岭回归在连续范数尺度上的首批最优速率,这些范数在 $L_2$ 与假设空间之间插值,而假设空间被视为向量值再生核 Hilbert 空间。这些速率能够处理错误设定情形,即真实回归函数并不包含于假设空间中。我们将关于假设空间容量的标准假设与一种新颖的向量值插值空间张量积构造相结合,以刻画回归函数的光滑性。我们的上界不仅达到了与实值核岭回归相同的速率,还去除了目标回归函数有界的假设。对于下界,我们利用投影论证将该问题归约到标量情形。我们证明这些速率在大多数情况下都是最优的,并且与输出空间的维度无关。我们还针对向量值 Sobolev 空间这一特殊情形说明了所得结果。
英文摘要:
We present the first optimal rates for infinite-dimensional vector-valued ridge regression on a continuous scale of norms that interpolate between $L_2$ and the hypothesis space, which we consider as a vector-valued reproducing kernel Hilbert space. These rates allow to treat the misspecified case in which the true regression function is not contained in the hypothesis space. We combine standard assumptions on the capacity of the hypothesis space with a novel tensor product construction of vector-valued interpolation spaces in order to characterize the smoothness of the regression function. Our upper bound not only attains the same rate as real-valued kernel ridge regression, but also removes the assumption that the target regression function is bounded. For the lower bound, we reduce the problem to the scalar setting using a projection argument. We show that these rates are optimal in most cases and independent of the dimension of the output space. We illustrate our results for the special case of vector-valued Sobolev spaces.
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。