l\_all\_since($L$;$T$;$a$;$x$.$P$($x$)) $\,\equiv$$_{\mbox{\scriptsize def}}$$\;\;$$P$($a$) \& ($\forall$$b$:$T$. $a$ before $b$ $\in$ $L$ $\in$ $T$ $\Rightarrow$ $P$($b$))