We establish optimal rates for online regression for arbitrary classes of
regression functions in terms of the sequential entropy introduced in (Rakhlin,
Sridharan, Tewari, 2010). The optimal rates are shown to exhibit a phase
transition analogous to the i.i.d./statistical learning case, studied in
(Rakhlin, Sridharan, Tsybakov 2013). In the frequently encountered situation
when sequential entropy and i.i.d. empirical entropy match, our results point
to the interesting phenomenon that the rates for statistical learning with
squared loss and online nonparametric regression are the same.
In addition to a non-algorithmic study of minimax regret, we exhibit a
generic forecaster that enjoys the established optimal rates. We also provide a
recipe for designing online regression algorithms that can be computationally
efficient. We illustrate the techniques by deriving existing and new
forecasters for the case of finite experts and for online linear regression.

基于顺序熵，确立了在线回归的最佳速率，发现最佳速率具有类似于独立同分布 / 统计学习情况的相变。此外，展示了一种享有建立的最佳速率的通用预测器和一种设计在线回归算法且计算高效的方法。