[SCIP] Questions regarding B&P framework for max problem.

[Shin, Jungeun]

Dear SCIP users

I am trying to solve maximization problem using B&P framework and found a few things I can’t understand from my knowledge.

My problem is defined as follows,

Max cx
Ax=1     ——— constraint (1)
Bx - Dy <=0 ——constraint (2)
0<= x <= 1
y binary

Pricing problem generates x columns and here are some questions that I have.

1) I thought that its dual problem should give upperbound and the dual multiplier of (2) is non-negative.  However, getDualsolLinear(2) returns negative values. 

2) The cost vector c has all positive elements. When I try to get the lp relaxation value within the Pricer using getLPObjVal( -0.115) , it returns negative value, while the primalbound is positive value(0.106).

If I understood the primal-dual relationship correctly, from the above two observations, I suspect if the SCIP framework automatically convert maximization problem to minimization problem by changing cost 
vector signs ?? 

I might have made some mistakes while writing the model. I check that the problem is set to maximize. I can’t find other possibilities that could make this happen.
I would be grateful for any comment.

Thank you!