[Scip] why no branching came up in my branch-and-price code?

[XiangyongLi]

Dear all,

I am using SCIP to develop a branch-and-price code. I tried to solve 50 instances and found that the code terminate at the root node (say " SCIP Status : problem is solved [optimal solution found] "). Namely no branching came up and all my considered instances are optimally solved at the root node (so far I have not found an instances which cannot be optimally solved at the root node using current B&P code).  I think that it is impossible. I have checked the pricer which could produce correct new variable. Further at each call of pricer, I used SCIPgetNLPBranchCands(scip)  to get number of branching candidates for LP solution branching. It returned value of zero. It seems that the LP relaxations at the root node always returned integer solution. I doubt this result. Is there any method in SCIP to verify my above worry? Thanks.




Best regards.


Xiangyong Li
 
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