Talk:Control-Lyapunov function

$$f(x)$$ or $$f(x,u)$$?
At the start of the article, $$f$$ is function of the single variable $$x$$. And at the end is dependent of $$u$$ also. I think that the article should be changed to avoid this. To solve it I suppose that first equation can be changed to read:



\dot{x}(t)=f(x(t),\, u(t)), $$

Positive definiteness of $$V(x,u)$$
It should be made clear if positive definiteness of $$V$$ is withs respect to $$x$$ or both $$x$$ and $$u$$. I would say for the explanation that is only for $$x$$, but I feel that something is missing in the explanation. —Preceding unsigned comment added by 132.206.73.6 (talk) 01:56, 20 May 2010 (UTC)

Generality of Artstein's theorem
Isn't Artstein's theorem only valid for control-affine systems? - Saung Tadashi (talk) 04:01, 8 November 2019 (UTC)