Package fr.uga.pddl4j.heuristics.state

Class AdjustedSum2

java.lang.Object
fr.uga.pddl4j.heuristics.AbstractHeuristic
fr.uga.pddl4j.heuristics.state.AbstractStateHeuristic
fr.uga.pddl4j.heuristics.state.RelaxedGraphHeuristic
fr.uga.pddl4j.heuristics.state.AdjustedSum2
All Implemented Interfaces:
Heuristic, PlanningGraphHeuristic, StateHeuristic, Serializable
public final class AdjustedSum2 extends RelaxedGraphHeuristic
This class implement the adjusted sum 2 heuristic. This heuristic improves the adjusted sum heuristic by replacing the computation of the cost(S) by the used the relaxed plan heuristic. Now, we have the following heuristic: 
 hadjsum2(S) := cost(S) + delta(S)
where
  • cost(S) := 1 + cost(S + prec(a) - add(a))
  • delta(S) := lev(S) - max(lev(p)) for all p in S
Warning: The adjusted sum heuristic is not admissible.
See Also:
AdjustedSum, Max, FastForward, Sum, Serialized Form

  • Constructor Details

    • AdjustedSum2

      public AdjustedSum2​(Problem problem)
      Creates a new AdjustedSum2 heuristic for a specified planning problem.
      Parameters:
      problem - the planning problem.
      Throws:
      NullPointerException - if problem == null.

  • Method Details

    • estimate

      public int estimate​(State state, Condition goal)
      Return the estimated distance to the goal to reach the specified state. If the return value is Integer.MAX_VALUE, it means that the goal is unreachable from the specified state.
      Parameters:
      state - the state from which the distance to the goal must be estimated.
      goal - the goal expression.
      Returns:
      the distance to the goal state from the specified state.

    • estimate

      public double estimate​(Node node, Condition goal)
      Return the estimated distance to the goal to reach the specified state. If the return value is DOUBLE.MAX_VALUE, it means that the goal is unreachable from the specified state.
      Parameters:
      node - the state from which the distance to the goal must be estimated.
      goal - the goal expression.
      Returns:
      the distance to the goal state from the specified state.