\begin{tabbing}
$\forall$\=$T$:Type, ${\it eq}$:EqDecider($T$), ${\it es}$:event\_system\{i:l\}, $x$:Id, $e$:\{\=$e$:es{-}E(${\it es}$)$\mid$ \+\+
\\[0ex]es{-}dtype(${\it es}$; loc($e$); $x$; $T$)\} ,
\-\\[0ex]$t$:rationals. ($x$ unchanged{-}for $t$ @ $e$) $\in$ prop\{i:l\}
\-
\end{tabbing}