@$i$:$k$ sends only on links in $L$
\\[0ex]$\,\equiv$$_{\mbox{\scriptsize def}}$$\;\;$$\forall$$e$@$i$. kind($e$) $=$ $k$ $\Rightarrow$ ($\forall$$l$:IdLnk. $\neg$($l$ $\in$ $L$) $\Rightarrow$ sends($l$;$e$) $=$ nil)