Paper detail

A spectral-like decomposition for transitive Anosov flows in dimension three

Given a (transitive or non-transitive) Anosov vector field $X$ on a closed three-dimensional manifold $M$, one may try to decompose $(M,X)$ by cutting $M$ along two-tori transverse to $X$. We prove that one can find a finite collection $\{T_1,\dots,T_n\}$ of pairwise disjoint, pairwise non-parallel incompressible tori transverse to $X$, such that the maximal invariant sets $Λ_1,\dots,Λ_m$ of the connected components $V_1,\dots,V_m$ of $M-(T_1\cup\dots\cup T_n)$ satisfy the following properties: 1, each $Λ_i$ is a compact invariant locally maximal transitive set for $X$, 2, the collection $\{Λ_1,\dots,Λ_m\}$ is canonically attached to the pair $(M,X)$ (i.e., it can be defined independently of the collection of tori $\{T_1,\dots,T_n\}$), 3, the $Λ_i$'s are the smallest possible: for every (possibly infinite) collection $\{S_i\}_{i\in I}$ of tori transverse to $X$, the $Λ_i$'s are contained in the maximal invariant set of $M-\cup_i S_i$. To a certain extent, the sets $Λ_1,\dots,Λ_m$ are analogs (for Anosov vector field in dimension 3) of the basic pieces which appear in the spectral decomposition of a non-transitive axiom A vector field. Then we discuss the uniqueness of such a decomposition: we prove that the pieces of the decomposition $V_1,\dots,V_m$, equipped with the restriction of the Anosov vector field $X$, are "almost unique up to topological equivalence".