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The Chetaev instability theorem for
dynamical system In mathematics, a dynamical system is a system in which a function describes the time dependence of a point in an ambient space. Examples include the mathematical models that describe the swinging of a clock pendulum, the flow of water i ...
s states that if there exists, for the system \dot = X(\textbf) with an
equilibrium point In mathematics, specifically in differential equations, an equilibrium point is a constant solution to a differential equation. Formal definition The point \tilde\in \mathbb^n is an equilibrium point for the differential equation :\frac = \m ...
at the origin, a continuously differentiable function V(x) such that # the origin is a boundary point of the set G = \; # there exists a neighborhood U of the origin such that \dot(\textbf)>0 for all \mathbf \in G \cap U then the origin is an unstable equilibrium point of the system. This theorem is somewhat less restrictive than the Lyapunov instability theorems, since a complete sphere (circle) around the origin for which V and \dot both are of the same sign does not have to be produced. It is named after Nicolai Gurevich Chetaev.


Applications

Chetaev instability theorem has been used to analyze the unfolding dynamics of proteins under the effect of optical tweezers.


See also

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Lyapunov function In the theory of ordinary differential equations (ODEs), Lyapunov functions, named after Aleksandr Lyapunov, are scalar functions that may be used to prove the stability of an equilibrium of an ODE. Lyapunov functions (also called Lyapunov’s se ...
— a function whose existence guarantees stability


References

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Further reading

*{{cite journal , doi=10.4249/scholarpedia.4672, doi-access=free , title=Chetaev function , year=2007 , last1=Shnol , first1=Emmanuil , journal=
Scholarpedia ''Scholarpedia'' is an English-language wiki-based online encyclopedia with features commonly associated with open-access online academic journals, which aims to have quality content in science and medicine. ''Scholarpedia'' articles are written ...
, volume=2 , issue=9 , page=4672 , bibcode=2007SchpJ...2.4672S Theorems in dynamical systems Stability theory