$\forall$${\it es}$:ES, $l$:IdLnk, ${\it tg}$:Id, $P$:(\{$e$:E$\mid$ $\uparrow$isrcv($e$)\} $\rightarrow\mathbb{P}$). ($\forall$$e$=rcv($l$,${\it tg}$). $P$($e$)) $\in$ $\mathbb{P}$