If the ergodic transformations S, T generate a free action on a finite non-atomic measure space (X,S,µ) then for any there exists a measurable function f on X for which and -almost everywhere as N → ∞. In the special case when S, T are rationally independent rotations of the circle this result answers a question of M. Laczkovich.
@article{bwmeta1.element.bwnjournal-article-fmv160i3p247bwm, author = {Zolt\'an Buczolich}, title = {Ergodic averages and free $$\mathbb{Z}$^2$ actions}, journal = {Fundamenta Mathematicae}, volume = {159}, year = {1999}, pages = {247-254}, zbl = {0944.37002}, language = {en}, url = {http://dml.mathdoc.fr/item/bwmeta1.element.bwnjournal-article-fmv160i3p247bwm} }
Buczolich, Zoltán. Ergodic averages and free $ℤ^2$ actions. Fundamenta Mathematicae, Tome 159 (1999) pp. 247-254. http://gdmltest.u-ga.fr/item/bwmeta1.element.bwnjournal-article-fmv160i3p247bwm/
[00000] [Bu] Z. Buczolich, Arithmetic averages of rotations of measurable functions, Ergodic Theory Dynam. Systems 16 (1996), 1185-1196. | Zbl 0869.28008
[00001] [M] P. Major, A counterexample in ergodic theory, Acta Sci. Math. (Szeged) 62 (1996), 247-258. | Zbl 0864.47002
[00002] [OW] D. O. Ornstein and B. Weiss, Ergodic theory of amenable group actions. I: the Rohlin lemma, Bull. Amer. Math. Soc. 2 (1980), 161-164. | Zbl 0427.28018
[00003] [P] W. F. Pfeffer, The Riemann Approach to Integration, Cambridge Univ. Press, Cambridge, 1993. | Zbl 0804.26005
[00004] [S] R. Svetic, A function with locally uncountable rotation set, Acta Math. Hungar., to appear. | Zbl 0963.28013