$\forall$${\it the\_es}$:ES, $T$:Type, $f$:(Id$\rightarrow$$T$), $g$:(IdLnk$\rightarrow$Id$\rightarrow$$T$), $e$:E.
\\[0ex]case(kind($e$))act($a$) =$>$ $f$($a$)rcv($l$,${\it tg}$) =$>$ $g$($l$,${\it tg}$) $\in$ $T$