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

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

    • 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.