Package fr.uga.pddl4j.heuristics.state

Interface StateHeuristic

All Superinterfaces:
Heuristic, Serializable
All Known Subinterfaces:
PlanningGraphHeuristic
All Known Implementing Classes:
AbstractStateHeuristic, AdjustedSum, AdjustedSum2, AjustedSum2M, Combo, CriticalPath, FastForward, GraphHeuristic, Max, RelaxedGraphHeuristic, SetLevel, Sum, SumMutex
public interface StateHeuristic extends Heuristic
This interface defines the methods accessible from all goal cost heuristics. An goal cost heuristic is a function that estimates the remaining distance to the goal. In order to find this estimation an heuristic function tries to solve a relaxed problem.

To have an good overview of the planning heuristics developed in this package see D. Bryce and S. Kambhampati. "A Tutorial on Planning Graph Based Reachability Heuristics", 2006.

  • Nested Class Summary

    Nested Classes
    Modifier and Type
    Interface
    Description
    static class 
    StateHeuristic.Name
    The name of heuristics.

  • Method Summary

    Modifier and Type
    Method
    Description
    double
    estimate​(Node node, Condition goal)
    Return the estimated distance to the goal to reach the specified state.
    int
    estimate​(State state, Condition goal)
    Return the estimated distance to the goal to reach the specified state.
    static StateHeuristic
    getInstance​(StateHeuristic.Name name, Problem problem)
    Create an instance of a goal cost heuristic for a specified problem.
    boolean
    isAdmissible()
    Returns true if this heuristic is admissible.

  • Method Details

    • estimate

      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

      double estimate​(Node node, 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:
      node - the ndoe 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.

    • isAdmissible

      boolean isAdmissible()
      Returns true if this heuristic is admissible.
      Returns:
      true if this heuristic is admissible.

    • getInstance

      static StateHeuristic getInstance​(StateHeuristic.Name name, Problem problem)
      Create an instance of a goal cost heuristic for a specified problem.
      Parameters:
      name - the name of the heuristic to create.
      problem - the problem for which the heuristic is created.
      Returns:
      the heuristic created.