[Scip] Changing the bounds of a FIXED variable

[Gerald Gamrath]

Dear Vivek,

1) If a variable is fixed to some value, both bounds get changed to that
value. Why do you want to change the bounds afterwards? Do you want to
relax them? That is not possible during the solving process (because it
would mean that all the dual bound computed so far, nodes cut off, etc.
might be wrong because they were based on the fixing).
2) During solving, you also cannot just delete variables, because of
similar reasons and some more (the variable might be part of a solution,
SCIP might have branched on it,...). However, you can mark them to be
deleted automatically during pricing and if they aged out of the LP at
the node where they were created, they will automatically be deleted, if
possible. Please have a look at the FAQ where this is described in more
detail: http://scip.zib.de/doc/html/FAQ.shtml#Q5.11

Best,
Gerald

On 11.03.2013 16:47, Vivek Periaraj wrote:
> Hello,
>
> 1) Is there a way to change the bounds of a fixed variable? I fix it using SCIPfixVar() but SCIPchgVarLb() and SCIPchgVarUb() does not allow me to change the bounds.
> 2) How to delete a variable from the problem object. If I do SCIPdelVar(), the variable is marked for deletion but it's not deleted from the problem object.
>
> Regards, 
> Vivek 
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