A model $m$ is AGI iff
$$ \left\| \frac{\partial}{\partial w} m\right\| \gg 0 $$
where $w$ is the world (not a model of the world).
Notice the partial derivative, time should be treated as a constant, the definition should NOT be interpreted as when the world changes, the model changes; instead, it is as the world changes, the model changes. It is not the now-world compare to a future-world/past-world; it is this-world compare to another different world. It’s more appropriate to think of as comparing to a parallel universe, as the world being different, the model shall be different.
$$ \lim_{t \rightarrow \infty} m \cong w $$
(assume AGI technology monotonically increases with time $t$)