[Scip] Column generation + branch and bound (from binpacking example)

[Luigi Malagò]

hi list,
i'm stuck again with my code, even if now the problem is with
branch and bound and the binpacking example. i have some unexpected
behavior and i dont understand where is the problem. maybe some of you can
help...

i'm working on the existing code of binpacking, to add my variables and
adapt to my problem,
since my example is similar in practice to the binpacking. i have
extra variables both in the master and in the pricing problem, all
continuous.

my question is about the SCIP_DECL_BRANCHEXECLP(branchExeclpRyanFoster)
callback.
i understand tha Ryan Foster branching, and i want to implement it also in
my problem.
since the binary variables of the master of the binpacking example are the
only
binary variables in my master, i think the code should be exacly the same.
nevertheless i have some problems:

when branching the first time, the SCIPgetLPBranchCands function returns 4
variables,
my problem is that the 1st and 3rd, and 2nd and 4th, respectively, have the
same name, but different
fractional value that (in both cases) sum to 1 (the value is then saved in
pairweights).
as a consequence bestvalue equals 0, and the assert then fails.

i dont know if i'm right, but i expect only 2 variables to appear in the
array
obtained with SCIPgetLPBranchCands. first i tought i had duplicate variables
in my problem.
i checked the value of the pointers to these 4 vars contained in lpcands,
the 1st and 2nd pointers to vars correspond to some variables that appear
among the
vars of probdata, while the other two do not appear among that list.
i obtained this list with SCIPgetVars(scip), where i correcly see the
original master variables, plus all that i have added at each iteration of
the master/pricer loop.

i guess something is wrong with my code, but if the variables are not
duplicated in the problem, i have no idea why i obtain duplicate variables
then... any idea that could help?

once again, thanks a lot for your help,
luigi malagò
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