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Dec 14, 2023 at 18:32 comment added tony The conclusion holds if the system is gradient, and the energy function is real analytic, and all undesirable equilibria are exponentially unstable.
Jan 22, 2022 at 10:10 history edited Rodrigo de Azevedo CC BY-SA 4.0
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Jan 22, 2022 at 5:49 comment added Pietro Majer It is easy to make a smooth field in $\mathbb R^n$ whose flow has a (degenerate) rest point x, such that the unstable manifold of x is e.g. a line and the the basin of attraction of x has non-empty interior. So maybe the question needs clarification on the definitions.
Jan 22, 2022 at 3:16 comment added Fabian Wirth To support the comment of @PietroMajer: We know examples of fixed points that are attractive but not stable (in the sense of Lyapunov). Here attractive means that a neighborhood of the fixed point is attracted to it. So the claim of the theorem cannot be true. A famous example is due to Vinograd (1957), explained in Hahn, Stability of Motion, p.191.
Jan 21, 2022 at 23:11 comment added Pietro Majer As it is written it is false, unless you have in mind a special definition of “unstable equilibrium” (you should include it). Note that A has no role.
Jan 21, 2022 at 21:29 comment added RLip2 Through a related question, generated by posting this question, I found the answer.
Jan 21, 2022 at 17:48 comment added RLip2 For example a saddle point. In particular, an equilibrium point for which the derivative of g has at least eigenvalue with real part > 0
S Jan 21, 2022 at 6:11 review First questions
Jan 21, 2022 at 6:25
S Jan 21, 2022 at 6:11 history asked RLip2 CC BY-SA 4.0