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  • Latest Post - ‏2012-12-13T15:33:40Z by SystemAdmin
SystemAdmin
SystemAdmin
7929 Posts

Pinned topic Conflict Refiner questions

‏2012-12-11T14:44:22Z |
Hello,
I tried to use the IISs in CSP infeasible to provide explanations of infaisabilié, and for that I use the function ConflcitRefiner of CPLEX.
I have difficulty in knowing how the function ConflictRefiner CPO / CPLEX?
Is that the function ConflictRefiner uses QuickXplain algorithm of Mr. Ulrich Junker? Or is this a known algorithms developed in the linear programming community?

if I change the order between the constraints of CSP infeasible input, output ConflictRefiner change.
It is said that it is QuickXplain which is used as QuickXplain is sensitive to the order between constraints.

Can you give me a clear definition (formal?) Of the output ConflictRefiner?
Is this a MIN-UNCSP a MIN-IIS ... ?
what is the algorithm behind the Conflict Refiner function ?
Why is it sensitive to the order between constraints?
thank you
Updated on 2012-12-13T15:33:40Z at 2012-12-13T15:33:40Z by SystemAdmin
  • SystemAdmin
    SystemAdmin
    7929 Posts

    Re: Conflict Refiner questions

    ‏2012-12-13T08:58:37Z  
    Hi,
    I am looking for the algorithm behind the function conflict Refiner of CPLEX, knowing that we have that informals descriptions for this function.
    Thank you
  • SystemAdmin
    SystemAdmin
    7929 Posts

    Re: Conflict Refiner questions

    ‏2012-12-13T13:19:05Z  
    Hi,
    I am looking for the algorithm behind the function conflict Refiner of CPLEX, knowing that we have that informals descriptions for this function.
    Thank you
    I think this question was answered here.
  • SystemAdmin
    SystemAdmin
    7929 Posts

    Re: Conflict Refiner questions

    ‏2012-12-13T14:36:44Z  
    I think this question was answered here.
    Thank you for your reply Friend,
    According to the response of PaulRubin, we see clearly that there is no difference between the output and the conflict refiner output IIS finder. Normally and from what I've read the documentation CPLEX, the output of IIS finder is an irreducible inconsistent set so that the output of Conflict refiner is not necessarily an IIS (irreducible inconsistent set), the heuristic behind Conflict refiner "black box CPLEX" find the minimal inconsistent set of constraints (th set is not necessarily irreducible).
    I want to know this heuristic algorithm (function Conflict refiner) :)
    Thank you for your help
  • SystemAdmin
    SystemAdmin
    7929 Posts

    Re: Conflict Refiner questions

    ‏2012-12-13T15:33:40Z  
    Thank you for your reply Friend,
    According to the response of PaulRubin, we see clearly that there is no difference between the output and the conflict refiner output IIS finder. Normally and from what I've read the documentation CPLEX, the output of IIS finder is an irreducible inconsistent set so that the output of Conflict refiner is not necessarily an IIS (irreducible inconsistent set), the heuristic behind Conflict refiner "black box CPLEX" find the minimal inconsistent set of constraints (th set is not necessarily irreducible).
    I want to know this heuristic algorithm (function Conflict refiner) :)
    Thank you for your help
    If you run the conflict refiner on a full LP or QP and use neither preferences nor constraint groups then the resulting minimal conflict will always be an IIS. Hence a minimal conflict will always be irreducible. So it is not clear to me why you are trying to make a distinction between the two concepts here. Some more details about IIS vs. conflicts can be found in the user manual.
    As Tobias already said in the thread that I quoted: The conflict refiner algorithm is basically a version of QuickXPlain by Ulrich Junker (2004).
    That is the algorithm that the conflict refiner uses internally.