We present a very quick and easy proof of the classical Stepanov-Hopf ratio ergodic theorem, deriving it from Birkhoff's ergodic theorem by a simple inducing argument.
@article{bwmeta1.element.bwnjournal-article-doi-10_4064-cm101-2-11, author = {Roland Zweim\"uller}, title = {Hopf's ratio ergodic theorem by inducing}, journal = {Colloquium Mathematicae}, volume = {100}, year = {2004}, pages = {289-292}, zbl = {1065.28010}, language = {en}, url = {http://dml.mathdoc.fr/item/bwmeta1.element.bwnjournal-article-doi-10_4064-cm101-2-11} }
Roland Zweimüller. Hopf's ratio ergodic theorem by inducing. Colloquium Mathematicae, Tome 100 (2004) pp. 289-292. http://gdmltest.u-ga.fr/item/bwmeta1.element.bwnjournal-article-doi-10_4064-cm101-2-11/