[Lemon-user] Lemon usage and cycles

[Pierre Moulon]

Hi,

I have done some experiments:

I have observed that lemon::biEdgeConnected(g) with an empty graph return
true.
Does it is normal ? (an empty graph do not have any connection, so how it
could have a biedge ?)

typedef lemon::ListGraph Graph;
Graph g;
std::cout << lemon::biEdgeConnected(g);


BTW, biEdgeConnectedCutEdges() seems to perform the job I need. Thanks a
lot for your tip !

But I don't understand how I remove the edges and empty nodes from the
graph that the cutMap send me.

Could you give me again pointer to do that (or an example of the library) ?

Sorry to be such a newbie under your great lemon library.

Regards,
Pierre


2012/8/1 Pierre Moulon <pmoulon at gmail.com>

> Thanks a lot I will try it ;-) and keep you updated if it fit my needs !
>
>
> 2012/8/1 Balázs Dezső <deba.mf at gmail.com>
>
>> Hi Pierre,
>>
>> I have answer for the first question. You just have to use the
>> biEdgeConnectedCutEdges() function, and remove the selected edges and then
>> the isolated nodes:
>>
>> http://lemon.cs.elte.hu/pub/doc/1.2.3/a00538.html#gafc18050604b516d4583e7595c5476078
>>
>> It is indeed linear time algorithm. I think, your algorithm doesn't
>> really work, because it will keep cut edges, i.e. edges connecting two
>> biconnected components.
>>
>> Balazs
>> On Aug 1, 2012 9:13 AM, "Pierre Moulon" <pmoulon at gmail.com> wrote:
>>
>>>  Hi,
>>>
>>> First congratulation for the great lemon library contribution.
>>>
>>> I have some question in order to obtain tips to realize some operation
>>> under lemon, so I ask to the mailing list.
>>>
>>> 1. Considering a graph, I want to keep only the edge and nodes of the
>>> graph that belong to cycles.
>>>
>>> i.e:
>>>   _____
>>> _|___|
>>>   |_|_|
>>>
>>> Must give :
>>>   ___
>>>   |___|
>>>   |_|_|
>>>
>>> Do you have any ideas about algorithms to realize this objective ?
>>> Removing node with 1 connexity can work bust must be iterated since the
>>> 1connexity is not satisfied on the graph. (iterative manner).
>>> i.e : _.__._
>>> Will remove the first edge and after a not cyling graph will remain.
>>>  .__._
>>> one more iteration
>>> ._.
>>> one more iteration
>>> All edges and nodes have been removed.
>>>
>>> I think there can be better approach that are linear with the graph size.
>>>
>>> 2. Considering this loopy graph I want select many random cycle :
>>>
>>> Any suggestion ?
>>>
>>> Thanks in advance for any help of tips ;-)
>>>
>>> --
>>> Regards/Cordialement,
>>> Pierre M
>>>
>>>
>>> _______________________________________________
>>> Lemon-user mailing list
>>> Lemon-user at lemon.cs.elte.hu
>>> http://lemon.cs.elte.hu/mailman/listinfo/lemon-user
>>>
>>>
>
>
> --
> Regards/Cordialement,
> Pierre M
>
>
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