Re: [Boost-users] Directed cycle detection in a DAG between two nodes

Subject: Re: [Boost-users] Directed cycle detection in a DAG between two nodes
From: Michael Powell (mwpowellhtx_at_[hidden])
Date: 2013-02-20 07:41:26

I can't speak to how your graph is wired up, but it seems to me that
somehow you need to keep track of nodes visited, more than simply nodeInit
(possibly).

I didn't do this in C++ boost, per se, but I have done something similar in
C# .NET using PowerCollections Graph. I had different node traversals
analyzing volumetric flow (pipes, substance, etc) through different
connectors (valves, and such), and needed to analyze communication between
volumes.

Enter graph traversal. I ended up keeping track of nodes visited to detect
my terminal case. Very fast, very clean, if a little inefficient because of
the overhead needing a collection (list, C++ STL vector if you will). You
pass in a new vector<> and could be the same one throughout the recursive
call.

Worked like a charm.

Good hunting!

Regards,

Michael

On Wed, Feb 20, 2013 at 4:20 AM, Amanullah Yasin <amanyasin_at_[hidden]>wrote:

> Hi,
>
> In Hill Climbing algorithm, before applying an operation "add_edge",
> "reverse_edge" or "remove_edge", I need to check whether the graph will be
> a Directed Acyclic Graph (DAG) or not. So there is recursive function but
> in some cases it goes in infinite loop and gives "stack overflow" error.
> //======= Function =======
> bool myAlgo::remainsADAG(const Node_type& nodeInit, const Node_type&
> node,  const Graph_type& graph)
> {
>   graph_traits<Graph_type>::adjacency_iterator vi, vi_end;
>   tie(vi, vi_end) = adjacent_vertices(node, graph);
>
>   for (; vi != vi_end; ++vi) {
>     if ((*vi == nodeInit) || (!remainsADAG(nodeInit, *vi, graph)))
>       return false;
>   }
>   return true;
> }
> ==============
> e.g. for Graph
> 12->19->20->23
> 19->24->31->18>19
> 18->32
>
> To test if there is a directed path between v12 and v32
> it goes as:
> 12->19->20->23
> 24->31->18>19
>
> *There is an infinite loop{18->19->20->23, 24->31->18}.*
> =================
> Can some one help me or is there any other easy way to find a directed
> path between two nodes in boost graph?
>
> Thanks in advance.
> YASIN
>
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