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Because flowmaps are homeomorphic maps, I was wondering if there is any literature that proves that diffeomorphism $\Phi(x)$ can be expressed as a flowmap of a certain dynamical system?

that is, does there exist $\dot z(t)=v(z(t))$ with initial value $z(0)=x$ such that $\Phi(x)=\phi_v^\tau(x)$ where $\phi_v^\tau(x)=z(\tau)$?

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No, this is usually not possible. There's a previous MO question discussing this, but to add to the material there:

  • A time-one map $\phi_1$ commutes with the 1-parameter family of diffeomorphisms $\phi_t$. However, The C1 generic diffeomorphism has trivial centralizer (Bonatti, Crovisier, Wilkinson). So being a time-one map is a rare property, in a sense!
  • One very simple obstruction can arise if $\Phi$ has periodic points. For a flow map, a point with period greater than one must correspond to a closed orbit, so the derivative must have at least one eigenvalue of 1. This, too, is a rare property.
  • Another set of concrete examples: consider diffeomorphisms of $\mathbb{R}^2$, which can have complicated chaotic dynamics. For flows in $\mathbb{R}^2$, you can't have chaos: recurrence is constrained to be relatively simple, by the Poincare-Bendixson theorem.
Martin M. W.
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  • Thanks! But I found a paper that shows diffeomorphism can be approximated by flowmaps, do you have any comments on this paper? https://www.sciencedirect.com/science/article/pii/S1474667016448974

    This seems to contradict the chaos you mentioned.

    – li ang Duan Nov 16 '23 at 06:38
  • I believe that paper involves time-varying vector fields, which gives you a lot more freedom. – Martin M. W. Nov 16 '23 at 11:31