In game theory, a equilibrium is:
Stable, if a perturbation form any of the players returns the equilibrium back to it's original state
Unstable, if a perturbation moves the equilibrium away from the original state
Semi-stable if some of the players perturbations are acceptable.
What do you call an equilibrium if a perturbation merely moves it slightly.
Consider the following game: Two players must state a number. Each of them gets a payoff of $1 if they state the same number, otherwise there is no payoff. (1,1) is an equilibrium. If one of the players chooses a different strategy, say 1.01. Then the Equilibrium is (1.01, 1.01). This does not seem unstable - neither does this seem stable. What is this type of equilibrium called?
EDIT: Based on comment below. I am trying to differentiate between equilibria where $\epsilon$ and $\epsilon + \delta$ perturbation will cause the same change for a sufficiently small $\delta$ and $\epsilon$ vs when the two perturbations $\epsilon$, and $\epsilon+\delta$ will each cause a different perturbation, as in the example above.