## Cohomological equations of Riemannian flows and the Anosov diffeomorphism. (Équations cohomologiques de flots riemanniens et de difféomorphismes d’Anosov.)(French)Zbl 1134.37001

On an oriented connected $$C^\infty$$ manifold M endowed with a diffeomorphism $$\gamma$$, let $$g\in C^\infty (M)$$ and $$X \in \Gamma^{\infty} (M)$$. If there exists $$f\in C^{\infty} (M)$$ such that $$f-f\circ\gamma = g$$ (resp. $$Xf =g$$), then $$f$$ is called a solution of the above discrete (resp. continuous) cohomological equation DCE (resp. CCE). The leafwise cohomology of a complete Riemannian Diophantine flow is computed here. Solving the DCE of $$(M,\gamma)$$ is equivalent to solve the CCE of the manifold endowed with the vector field obtained by the suspension of $$(M,\gamma)$$. The authors solve explicitly the DCE for the Anosov diffeomorphism on the torus $$\mathbb T^n$$ defined by a hyperbolic and diagonalizable matrix $$A\in \text{SL}(n,\mathbb Z)$$, whose eigenvalues are all some real positive numbers. This is then use to solve the CCE of the Anosov flow $$\mathcal F$$ on the hyperbolic torus $${\mathbb T_A}^{n+1}$$ obtained from $$A$$ by suspension. Therefore some other geometrical objects associated to $$A$$ and $$\mathcal F$$, like invariant distributions and the leafwise cohomology are computed here.

### MSC:

 37A05 Dynamical aspects of measure-preserving transformations 37C10 Dynamics induced by flows and semiflows 58A30 Vector distributions (subbundles of the tangent bundles) 53C12 Foliations (differential geometric aspects) 37D20 Uniformly hyperbolic systems (expanding, Anosov, Axiom A, etc.)

### Keywords:

invariant distributions; Anosov flows
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