Package edu.uky.ai.csp.kr

Class Solution

java.lang.Object
edu.uky.ai.csp.kr.Solution
All Implemented Interfaces:
java.lang.Cloneable
public class Solution
extends java.lang.Object
implements java.lang.Cloneable

A solution to a constraint satisfaction problem is an assignment of values to the problem's variables.

A solution is complete when every variable has exactly 1 value in its domain.

A solution can be a partial solution, meaning that we have not yet narrowed down the domains of all variables to a single value.

A solution is impossible if any of its assigned variables (those with 1 value in the domain) violate a constraint in the problem or if any variable has a domain with no values in it (i.e. no legal value).

Author:
Stephen G. Ware

  • Field Summary

    Fields 
    Modifier and Type Field Description
    Problem problem
    The problem this solution is potentially a solution for

  • Constructor Summary

    Constructors 
    Constructor Description
    Solution​(Problem problem)
    Constructs a new solution object for a given problem.

  • Method Summary

    Modifier and Type Method Description
    Solution clone()  
    int countDescendants()
    Returns the number of descendant solutions that were generated from this object.
    Domain getDomain​(Variable variable)
    Returns the domain (i.e.
    boolean isComplete()
    A solution is complete if every variable has a domain of size exactly 1 and none of the problem's constraints are violated.
    boolean isImpossible()
    A solution is impossible if any variable has a domain of size 0 (i.e.
    int size()
    The size of a solution is the sum of the sizes of all domains which have more than 1 value.
    boolean test​(Constraint constraint, java.lang.Object left, java.lang.Object right)
    Given some constraint and two candidate values for the constraint's variables, this method checks if the constraint would be violated by those values.
    java.lang.String toString()  

    Methods inherited from class java.lang.Object

    equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

  • Field Details

    • problem

      public final Problem problem
      The problem this solution is potentially a solution for

  • Constructor Details

    • Solution

      public Solution​(Problem problem)
      Constructs a new solution object for a given problem. The domains of all variables will be set to their domains in the initial state of the problem.
      Parameters:
      problem - the problem that this object will potentially be a solution for

  • Method Details

    • toString

      public java.lang.String toString()
      Overrides:
      toString in class java.lang.Object

    • clone

      public Solution clone()
      Overrides:
      clone in class java.lang.Object

    • countDescendants

      public int countDescendants()
      Returns the number of descendant solutions that were generated from this object.
      Returns:
      the number of descendants

    • isComplete

      public boolean isComplete()
      A solution is complete if every variable has a domain of size exactly 1 and none of the problem's constraints are violated.
      Returns:
      true if this solution is complete, false otherwise

    • isImpossible

      public boolean isImpossible()
      A solution is impossible if any variable has a domain of size 0 (i.e. no legal value) or if any of the problem's constraints have been violated.
      Returns:
      true if this solution can never be complete

    • size

      public int size()
      The size of a solution is the sum of the sizes of all domains which have more than 1 value. This implies that size is 0 for a complete solution. The size of a solution is a simple representation of how much work remains to be done before this solution is complete.
      Returns:
      the size of the solution

    • getDomain

      public Domain getDomain​(Variable variable)
      Returns the domain (i.e. the set of possible values) for a given variable in this solution.
      Parameters:
      variable - the variable
      Returns:
      the variable's domain

    • test

      public boolean test​(Constraint constraint, java.lang.Object left, java.lang.Object right)
      Given some constraint and two candidate values for the constraint's variables, this method checks if the constraint would be violated by those values.
      Parameters:
      constraint - the constraint to check
      left - the value for the constraint's left variable
      right - the value for the constraint's right variable
      Returns:
      true if the values do not violate the constraint, false otherwise