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Let $M$ be a connected and simply connected Riemannian manifold, non-compact, and suppose that $\{V_p\}_{p \in M}$ is a family of vector fields on $M$ indexed by $M$. Suppose moreover that the map $$ p\to V_p(x), $$ is smooth and define the differential equation $$ f_t' = V_p(f_t) ,\, f_0=p. \qquad (*) $$ So in $(*)$ there is an explicit dependence on $p$ both in the initial condition (IC) and in the "dynamics" of the ODE itself. Therefore, let's relabel this explicit dependence on $p$ of a solution to $(*)$ by $f_{t,p}$.

Let $X$ be the collection of all compactly-supported smooth vector-fields on $M$ such that

  • A solution $f_{t,p}$ exists up to time $1$ for each $p$,
  • The map taking $(V_p)_{p \in M}$ to the time $1$ solution of $(*)$ is a diffeomorphism,
  • $p\to V_p(x)$ is non-constant for at-least one value of $x\in M$.

Denote this latter map by $\widetilde{\operatorname{Exp}}:X\to \operatorname{Diff}_{c,0}(M)$. It is known, see this post for references, that if there is no dependence on $p$ then $\operatorname{Exp}$ generates $\operatorname{Diff}_{c,0}(M)$. Are such results known in this case, i.e.: where vector fields depend non-trivially on the ICs?

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  • $\begingroup$ Just to be sure, what is $\mathrm{Diff}_{c,0}$? $\endgroup$ May 8, 2020 at 15:15
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    $\begingroup$ It's the identity component of the space of $C^{\infty}$ diffeomorphisms with compact support (in the sense of A. Banyaga; namely that they are the identity outside some compact in M). $\endgroup$
    – ABIM
    May 8, 2020 at 15:17
  • $\begingroup$ Thanks. Got it. Here is another (dumb) question. Is $X$ nonempty? $\endgroup$ May 8, 2020 at 15:41
  • $\begingroup$ Yes, ofcourse, we assume that to be the case (it can be shown also). $\endgroup$
    – ABIM
    May 8, 2020 at 18:08

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