Abstract:
For a 1-periodic function $f$ of finite smoothness and a Diophantine vector $\alpha$ the solubility problem is studied for
the additive cohomological equation
on the torus
$$
w(T_\alpha x)-w(x)=f(x)-\int_{\mathbb T^d}f(t)\,dt,
$$
where $T_\alpha x=x+\alpha\pmod1$ is the shift of the torus $\mathbb T^d$
by the vector $\alpha$ and $w$ is an unknown measurable function.
Necessary and sufficient conditions are obtained for the conjugacy of a linear
flow on the $(d+1)$-torus
to the reparametrized flow $$
\begin{cases}
\dot x=\dfrac\alpha{F(x,y)}\,,\\
\dot y=\dfrac1{F(x,y)}\,,
\end{cases}
$$
where $F(x,y)$ is a positive 1-periodic function of
finite smoothness.