Originally posted by: SystemAdmin

[a_shraideh said:]

Hello every body,
i use cplex9 with java to solve Integer problem

i solve at first the problem with certain constraints and cplex give a solution within time T
i solve the same model but after adding some new constraint that will reduce and restrict  the search decision tree but the surprised was that cplex used more time than the first solution
What i know is that,  adding constraints to any problem will reduce the number of possible nodes to visit
is this suppose is correct or no??
thank you in advance

#DecisionOptimization
#MathematicalProgramming-General

Originally posted by: SystemAdmin

[prubin said:]

[quote author=a_shraideh link=topic=837.msg2494#msg2494 date=1232040471]
What i know is that,  adding constraints to any problem will reduce the number of possible nodes to visit


Not necessarily, and particularly not if they remove feasible solutions.  Consider an easy MIP model, in which we find an optimal solution early and then prune the remaining nodes based on bound.  Now add a constraint that makes the former optimal solution infeasible.  Without it, we may have to visit some or all of the nodes that previously were pruned.

/Paul

#DecisionOptimization
#MathematicalProgramming-General

Originally posted by: SystemAdmin

[a_shraideh said:]

Thank poul ,
your answere where really helpfull

#DecisionOptimization
#MathematicalProgramming-General