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Mar 8, 2017 at 13:14 comment added Benjamin Steinberg I agree with your equality
Mar 8, 2017 at 11:25 comment added user148455 Thank you for your answer. I guess your suggestion makes sense because, given a finitely generated semigroup $G$ with a probability measure $\nu$, we always have $\,\,\,\Sigma_{u\in G}\nu(u)=\Sigma_{y\in hG}\nu(h^{-1}y)=1\,\,$, right? I actually thought about your formula but I was concerned about the measure of $\nu(h^{-1}y)$. I think now the above observation shows that it's not an issue.
Mar 7, 2017 at 18:23 comment added Benjamin Steinberg I guess the natural analogue would be $\sum_{u\in G}f(hu)\nu(u)=\sum_{y\in hG}f(y)\nu(h^{-1}y)$ where $h^{-1}y=\{u\in G\mid hu=y\}$. Maybe some further restrictions on $f$ are needed to guarantee that the right hand side converges like if $|f|$ has a finite first moment.
Mar 7, 2017 at 13:28 comment added user148455 @Benjamin, Yes, $h$ is fixed while $g$ varies. My question is precisely how to make sense of formula $(1)$ in the framework of semigroups? Are there finitely generated semigroups that allow a similar relation? Perhaps the formula need to be reformulated but the main idea is to eliminate the dependence of $h^{-1}$ in the measure and have something related to $h$ or $h^{-1}$ in the argument of $f$ instead.
Mar 7, 2017 at 12:27 comment added Benjamin Steinberg I don't understand your formula in the semigroup case. Is h fixed? If so then how do you sum over hu and make sense of $\nu(u)$ if h is not left cancellable.
Mar 7, 2017 at 10:58 history asked user148455 CC BY-SA 3.0