Hallo Martin, I was going to use xdfWith from Data.Graph.Inductive.Query.DFS with Data.Graph.Inductive.Graph.out' as second argument, but 1. xdfWith is not exported 2. out' seems to be wrong (by looking at the source code) -- | All outward-directed 'LEdge's in a 'Context'. out' :: Context a b -> [LEdge b] out' c@(_,v,_,_) = map (\(l,w)->(w,v,l)) (context4l' c) ^^^ I think, the outgoing edge must be made as "(v,w,l)"! inn' looks correct: -- | All inward-directed 'LEdge's in a 'Context'. inn' :: Context a b -> [LEdge b] inn' c@(_,v,_,_) = map (\(l,w)->(w,v,l)) (context1l' c) Can 1. and 2. be fixed? I need the general xdfWith because I want to filter out some successors (or maybe I can filter to whole graph first). Cheers Christian