On The Existence of Globally Solvable Vector Fields in Smooth Manifolds
  Let $(\mathrm{M}, \omega_{0})$ be a connected paracompact smooth oriented manifold. We establish a necessary and sufficient conditions on Lie subalgebra $\mathfrak{a}$ of $\mathrm{T M}$ such that its orbits becomes diffeomorphic to an open convex set of $\mathbb{R}^{n}$, where $n$ is the orbit dimension. 
Jose Ruidival dos Santos Filho, Joaquim Tavares