Re: [Boost-users] [BGL] IncidenceGraph and out_edges

Subject: Re: [Boost-users] [BGL] IncidenceGraph and out_edges
From: Christian Bähnisch (christian-baehnisch_at_[hidden])
Date: 2009-06-15 08:13:56

You think not fulfilling this requirement should be no problem? I looked at the 
implementation of connected components and to me it seems as if out_edges 
together with the target function is used to traverse the vertex-ring of a 
vertex!

Am Montag, 15. Juni 2009 13:18:59 schrieb Andrew Sutton:
> > I'm trying to implement the IncidenceGraph concept for an non-BGL
> > undirected graph like datastructure. Following the boost documentation
> > the target function used with edges from out_edges(u,g) must give
> > vertices != u.
> >
> > Can somebody please explain me why this requirement is in BGL! I think it
> > can make the adaption very difficult as it requieres to artificially
> > orientate undirected edges for each call to out_edges. Any help would be
> > much appreciated!
>
> I'm not entirely sure. The constraint makes sense if you're building graphs
> that don't allow loops, but otherwise, it would not seem to be necessary.
> There's a small possibility that the requirement actually stemmed from an
> adjacency_list bug that caused problems when deleting loop edges, but the
> bug has since been fixed.
>
> I would say: do what you think is right for your own graph structure.
>
> Andrew Sutton
> andrew.n.sutton_at_[hidden]