da{-}outlinks(${\it da}$;$i$) $\,\equiv$$_{\mbox{\scriptsize def}}$$\;\;$mapfilter($\lambda$$k$.da{-}outlink{-}f(${\it da}$;$k$);$\lambda$$k$.has{-}src($i$;$k$);fpf{-}dom{-}list(${\it da}$))