$$ \def\E{\mathbb{E}} %expectation \def\P{\mathbb{P}} %prob \def\var{\mathbb{V}} %var \def\T{\mathrm{\scriptscriptstyle T}} %transpose \def\ind{\mathbbm{1}} %indicator \newcommand{\gw}[1]{\color{red}{(#1)}} \newcommand{\norm}[1]{\lVert#1\rVert} \newcommand{\abs}[1]{\lvert#1\rvert} $$

A short summary of paper: Andrea Caponnetto and Ernesto De Vito. Optimal rates for the regularized least-squares algorithm. Foundations of Computational Mathematics, 7(3):331–368, 2007.