Universal piecewise linear least squares prediction

We consider the problem of sequential prediction of real-valued sequences using piecewise linear models under the square-error loss function. In this context, we demonstrate a sequential algorithm for prediction whose accumulated squared error for every bounded sequence is asymptotically as small as that of the best fixed predictor for that sequence taken from the class of piecewise linear predictors. We also show that this predictor is optimal in certain settings in a particular min-max sense. This approach can also be applied to the class of piecewise constant predictors, for which a similar universal sequential algorithm can be derived with corresponding min-max optimality.