\begin{tabbing}
R{-}base{-}recognize($i$;${\it ds}$;$x$;$k$;$T$;${\it test}$)
\\[0ex]$\,\equiv$$_{\mbox{\scriptsize def}}$$\;\;$\=(@$i$ $x$ initially false$_{2}$:$\mathbb{B}$ $\oplus$ @$i$ only events in $k$.nil change $x$:$\mathbb{B}$)\+
\\[0ex]$\oplus$ @$i$ \=\+
\\[0ex]ef\=fect $k$(v:$T$)\+
\\[0ex]$x$ := $\lambda$$s$,$v$. if ${\it test}$($s$,$v$)$\rightarrow$ true$_{2}$ else $s$($x$) fi State(fpf{-}join(IdDeq;$x$ : $\mathbb{B}$;${\it ds}$)) v 
\-\-\-
\end{tabbing}