eventlist(${\it pred?}$;$e$)
\\[0ex]$\,\equiv$$_{\mbox{\scriptsize def}}$$\;\;$if first(${\it pred?}$;$e$)$\rightarrow$ $e$.nil else eventlist(${\it pred?}$;pred(${\it pred?}$;$e$)) @ ($e$.nil) fi
\\[0ex]\emph{(recursive)}