\begin{tabbing}
sends{-}on{-}pair($s$;$l$;${\it tg}$)
\\[0ex]$\,\equiv$$_{\mbox{\scriptsize def}}$$\;\;$\=reduce($\lambda$${\it kl}$,$x$. eqof(IdLnkDeq)(2of(${\it kl}$),$l$)\+
\\[0ex]$\wedge_{2}$ deq{-}member(IdDeq;${\it tg}$;map($\lambda$$z$.1of($z$);2of($s$)(${\it kl}$)))
\\[0ex]$\vee_{2}$ $x$;false$_{2}$;1of($s$))
\-
\end{tabbing}