Module org.cicirello.chips_n_salsa
Package org.cicirello.search.problems.scheduling

Class WeightedFlowtime

java.lang.Object
org.cicirello.search.problems.scheduling.WeightedFlowtime
All Implemented Interfaces:
IntegerCostOptimizationProblem<Permutation>, Problem<Permutation>, SingleMachineSchedulingProblem
public final class WeightedFlowtime extends Object implements SingleMachineSchedulingProblem
Implements the scheduling cost function known as weighted flowtime. The flowtime F[j] of job j is: F[j] = C[j] - r[j], where C[j] is the time it is completed by the machine, and r[j] is its release time. The weighted flowtime cost function is the weighted sum over the jobs of: w[j]F[j], where w[j] is job j's weight.

  • Constructor Details

    • WeightedFlowtime

      public WeightedFlowtime(SingleMachineSchedulingProblemData instanceData)
      Constructs a single machine scheduling problem for minimizing weighted flowtime.
      Parameters:
      instanceData - An encapsulation of the job characteristics, such as processing times, etc.

  • Method Details

    • getInstanceData

      public SingleMachineSchedulingProblemData getInstanceData()
      Description copied from interface: SingleMachineSchedulingProblem
      Gets an object that encapsulates the data describing the scheduling problem instance, such as number of jobs, and the characteristics of the jobs, such as processing times, setup times, due dates, weights, etc.
      Specified by:
      getInstanceData in interface SingleMachineSchedulingProblem
      Returns:
      an encapsulation of the data describing the scheduling problem instance

    • cost

      public int cost(Permutation candidate)
      Description copied from interface: IntegerCostOptimizationProblem
      Computes the cost of a candidate solution to the problem instance. The lower the cost, the more optimal the candidate solution.
      Specified by:
      cost in interface IntegerCostOptimizationProblem<Permutation>
      Parameters:
      candidate - The candidate solution to evaluate.
      Returns:
      The cost of the candidate solution. Lower cost means better solution.

    • value

      public int value(Permutation candidate)
      Description copied from interface: IntegerCostOptimizationProblem
      Computes the value of the candidate solution within the usual constraints and interpretation of the problem.
      Specified by:
      value in interface IntegerCostOptimizationProblem<Permutation>
      Parameters:
      candidate - The candidate solution to evaluate.
      Returns:
      The actual optimization value of the candidate solution.

    • minCost

      public int minCost()
      Description copied from interface: IntegerCostOptimizationProblem
      A lower bound on the minimum theoretical cost across all possible solutions to the problem instance, where lower cost implies better solution. The default implementation returns Integer.MIN_VALUE.
      Specified by:
      minCost in interface IntegerCostOptimizationProblem<Permutation>
      Returns:
      A lower bound on the minimum theoretical cost of the problem instance.