Class WeightedEarlinessTardiness

java.lang.Object
org.cicirello.search.problems.scheduling.WeightedEarlinessTardiness
All Implemented Interfaces:
IntegerCostOptimizationProblem<Permutation>, Problem<Permutation>, SingleMachineSchedulingProblem
public final class WeightedEarlinessTardiness extends Object implements SingleMachineSchedulingProblem
Implements the scheduling cost function known as weighted earliness plus weighted tardiness. The lateness L[j] of job j is: L[j] = C[j] - d[j], where C[j] is the time it is completed by the machine, and d[j] is its due date. The tardiness of job j is: T[j] = max(0, L[j]). That is, although lateness can be negative, tardiness is never negative (i.e., no reward for a job completing early). The earliness of a job j is: E[j] = max(0, -L[j]). The weighted earliness plus weighted tardiness problem involves a pair of weights for each job, a tardiness weight wt[j] and an earliness weight we[j]. The cost function is the weighted sum over the jobs of: wt[j]T[j] + we[j]E[j], where w[j] is job j's weight.

  • Constructor Details

    • WeightedEarlinessTardiness

      public WeightedEarlinessTardiness(SingleMachineSchedulingProblemData instanceData)
      Constructs a single machine scheduling problem for minimizing weighted earliness plus weighted tardiness.
      Parameters:
      instanceData - An encapsulation of the job characteristics, such as processing times, etc.
      Throws:
      IllegalArgumentException - if instanceData.hasDueDates() returns false.

  • Method Details

    • 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.