$\forall$$i$, $x$:Id, $T$:Type, ${\it ks}$:Knd List, $A$:Realizer.
\\[0ex]$\neg$R{-}occurs($A$;$i$;$x$) $\Rightarrow$ @$i$ only events in ${\it ks}$ change $x$:$T$ $\parallel$ $A$