Beta-strong elementary embedding ($\beta$-strong)

For inaccessible $\lambda$, a map $j:V_{\lambda }\to M$ with critical point $\kappa$ is $\beta$-strong when $M$ is transitive and $V_{\kappa +\beta }\subseteq M$.

A formula $\Phi (x,\kappa )$ defines a $\beta$-stable property of $\kappa$ when it is absolute between the universe and every transitive $M\supseteq V_{\kappa +\beta }$.

If a $\beta$-strong embedding has critical point $\kappa$ and the $\beta$-stable property $\Phi (\kappa )$ holds, then $\{\mu <\kappa :\Phi (\mu )\}$ is unbounded in $\kappa$. For each $\gamma <\kappa$, the target sees $\kappa$ as a witness between $\gamma$ and $j(\kappa )$; elementarity reflects a witness between $\gamma$ and $\kappa$.