[Scip] SCIPgetTransformedCons

[Jose Walteros]

Hi all, 

I was able to adapt the event_boundwriting example that you have in order to catch information when each node is processed. There are a couple of questions that I have about it:

1. As I see it base on the code in the file event_boundwriting.c when DEFAULT_WRITESUBMIPDUALBOUND option is as true, you construct a new model, copy the bounds, and then, solve it to find the value of the LP relaxation at that node. Is this correct?

2. As I mentioned before, something that I am noting is that SCIP is pruning nodes in the B&B tree that are not supposed to be pruned. SCIP is not even calling the pricer in those node (and because of this reason I don't even know if the LP relaxation is solved in this nodes). I would like to know if it is possible to use this handler do find why the node was pruned (if it was by bound or by infeasibility)? 

-Jose

On May 17, 2012, at 6:52 PM, Jose Walteros wrote:

> Hi all, 
> 
> I coded a Branch and price using the binpacking example as a a starting point. So far everything is working and the code is running, I was able to solve the previous problems that I had before. 
> 
> I am currently running some tests and I found that the pricer problem is not being called while solving some nodes in the b&b tree (my impression is that maybe the nodes are cut by infeasibility, but I want to be sure about the reason). What I have seen, at least for the instances that I am using, is that SCIP by default solves the tree using a depth first search (it might not be the case always, but for the instance that I am running, it explores the tree in this fashion). I am using as a branching rule a very similar rule compared to the Ryan Foster's, that comes with the binpacking example. I was wondering if there is a simple way to access the value of the objective function at each node and also to find out if the node was cut off (and the reason why it was cut off, i.e., cut by bound, or by infeasibility )? 
> 
> I think that doing this can be done by writing an event handler or something like that, but I have not seen a file like that in the examples that you have. 
> 
> Thanks for your help.
> 
> -Jose

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