Re: [boost] Re: Hypergraphs and the BGL

From: David A. Greene (greened_at_[hidden])
Date: 2002-04-26 13:24:03

Douglas Paul Gregor wrote:
>>I'd like to be able to take two independent BGL graphs and combine
>>them into one graph such that there is a set of well-defined
>>connections (i.e. it is easy for me to know what they should be)
>>from one graph to the other.  For me, it's usually just a single
>>edge, but the ability to more generally add edges between the
>>graphs would be useful -- there are other parts of my application
>>that can make use of that.
> 
> This would be a useful capability for sure.

Indeed.  Do we have any idea how to go about efficiently implementing
it?  I can try to put something together and post it to the files
section.  It would be useful to flesh out some ideas before I spend a
lot of time on it, though.  But this would be immediately useful to
me so there is some incentive to work on it.

>>But let me throw in the other twist: these independent graphs
>>are actually filtered_graphs.
>
> This isn't a twist in the BGL sense. A filtered_graph is just a graph
> adaptor. It's no different conceptually from any other type of graph.

Conceptually, yes.  Actually, no.  num_vertices, for example, does
not behave as one might expect (it behaves more like max_index + 1).
It probably does not matter much in the end, but it's useful to keep
these subtle differences in mind.

                                  -Dave
-- 
"Some little people have music in them, but Fats, he was all music,
  and you know how big he was."  --  James P. Johnson