\begin{tabbing}
es{-}trigger(${\it es}$;$i$;${\it knd}$;${\it ds}$;$f$)($e$)
\\[0ex]$\,\equiv$$_{\mbox{\scriptsize def}}$$\;\;$\=if es{-}kind(${\it es}$; $e$) = ${\it knd}$ $\wedge_{b}$ es{-}loc(${\it es}$; $e$) = $i$\+
\\[0ex]then '$f$(es{-}state{-}when(${\it es}$;$e$),es{-}val(${\it es}$; $e$))'
\\[0ex]else inr $\cdot$ 
\\[0ex]fi 
\-
\end{tabbing}