[Scip] Implementing new branching rule

[Gregor Hendel]

Am 18.12.2012 21:42, schrieb Siddhartha Jain:
> Hi Timo,
>
> Thanks for the reply. It's a research idea that I'm implementing.
>
> If the variables returned are those of the transformed problem, is 
> there a way for me to get the column index to which the variables 
> correspond to?
Hi Sid,

columns have two types of indices: A so-called 'index' (obtained via 
SCIPcolGetIndex()), which serves as a unique identifier for this column, 
and its current LP position, called 'LPpos'
(SCIPcolGetLPPos()). The latter is the actual index in the LP columns 
array (SCIPlpGetCols()), or -1, if the column is not part of the LP at 
the current tree node.

It depends on your idea which one you want to use.

Best regards,
gregor
>
> Thanks
> --Sid
>
>
> On Tue, Dec 18, 2012 at 3:16 PM, Timo Berthold <berthold at zib.de 
> <mailto:berthold at zib.de>> wrote:
>
>     Hi Sid,
>
>     this function gives you an array of SCIP_VAR pointers. These
>     variables are
>     variables in the transformed problem which have a fractional
>     solution in
>     the LP solution of the current node relaxation.
>
>     If you want to get the variable's problem index, you can call the
>     function
>     SCIPvarGetProbindex() with these variable pointers as input.
>
>     I am curious: what variant of strong branching do you plan to
>     implement?
>
>     I recommend you to look through the full strong branching and
>     maybe the
>     most fractional branching rule in SCIP to get an idea how they are
>     set up.
>
>     If not yet happened, I further recommend you to have a look at the
>     following points in the SCIP documentation:
>     http://scip.zib.de/doc/html/BRANCH.shtml
>     http://scip.zib.de/doc/html/scip_8h.shtml#a04924d1578c8b893f8420001445210fd
>     http://scip.zib.de/doc/html/pub__var_8h.shtml#a661c5d1f7f4e09471f8d2898b5bda91c
>
>     Also check out our FAQ.
>
>     Best regards,
>     Timo
>     > Hi,
>     >
>     > I'm implementing a variant of strong branching within SCIP. I was
>     > wondering
>     > - what do the lpcands obtained via the function SCIPgetLPBranchCands
>     > correspond to?
>     >
>     > Do they correspond to the original problem variables or the
>     constraint
>     > matrix variables after presolving, etc.
>     >
>     > How can I obtain the problem variable index/column index resp. the
>     > variable
>     > is referring too?
>     >
>     > Thanks
>     > --Sid
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