<div>Hi,</div><div> </div><div>During the implementation of my branch-and-price algorithm I have encountered a problem when while doing branching, in some nodes, the primal feasibility is being lost. I have tried to check the status by using <font face="Consolas"><font face="Consolas"><p>
getLpProblemPointer()->lp_solver->initialSolve() and it seems that initialSolve() is ending with an optimal solution where it is not the case when getLpProblemPointer()->lp_solver->resolve() is used. In the latter case, the optimal basis is not avaialble and the primal feasibility is being lost, for example, I get the following messages</p>
</font><p></p></font><p>LP: **** Processing NODE 7 on LEVEL 4 (dived) ****</p></div><div>LP: *** Starting iteration 1 ***<br>Clp0006I 0 Obj 1789 Primal inf 0.9999998 (2)<br>Clp0006I 1 Obj 1801<br>Clp0001I Primal infeasible - objective value 1801<br>
LP: Matrix size: 81 vars x 16 cuts<br>LP: Solution value: 1801.0000 / 36 , 1 <br>optimal basis is available () = 0<br></div><div>I should note that the during baranchig, I change the upper bounds of some of variables, based on my branching decision and also I am not using strong branching. Also, it is not possible for my relaxed master problems to have be primal infeasible because of the artificial variables that I have added in the restricted master problem for having a feasibl solution in each node after branching. </div>
<div>The LP Solver that I am using is CLP and I am using Bcp-1.3.4 verision.</div><div> </div><div>I appreciate any thoughts for this issue.</div><div> </div><div>Thanks,</div><div>Sepehr Nemati</div>