javax.constraints.impl.search.goal
Class SolverWithGoals

java.lang.Object
  javax.constraints.impl.search.AbstractSolver
      javax.constraints.impl.search.goal.SolverWithGoals

All Implemented Interfaces:

Solver

public abstract class SolverWithGoals
extends AbstractSolver

Constructor Summary

SolverWithGoals(Problem problem)

Method Summary

abstract Goal	and(Goal g1, Goal g2) Returns an "AND" Goal.
boolean	applySolution(Solution solution) This method tries to resolve the problem by applying the Solution "solution" to the problem, and returns true if "solution" satisfies all of the posted constraints, false otherwise.
abstract void	backtrack() This method forces a solver to "backtrack".
Goal	combineSearchStrategies()
boolean	execute(Goal goal) This methods is equivalent to execute(goal,ProblemState.DO_NOT_RESTORE);
abstract boolean	execute(Goal goal, ProblemState restoreOrNot)
Solution[]	findAllSolutions() This method attempts to find all solutions for the Problem.
Solution	findOptimalSolutionDichotomize(Objective objective, Var objectiveVar) The actual minimization algorithm executes a dichotomized search.
Solution	findSolution(ProblemState restoreOrNot) This method attempts to find a solution of the problem, for which the solver was defined.
abstract java.lang.Object	goalThis(Goal goal) To create a new goal on the javax.constraints level without necessity to go down to the underlying CP solver, one needs to use a goal that will serve as an implementation object.
Goal	goalVarEqValue(Var var, int value)
Goal	goalVarGeValue(Var var, int value)
Goal	goalVarLeValue(Var var, int value)
Goal	goalVarNeqValue(Var var, int value)
Goal	makeGoal(SearchStrategy strategy)
SearchStrategy	newSearchStrategy() This methods returns a new default search strategy
abstract Goal	or(Goal g1, Goal g2) Returns an "OR" Goal.
void	trace(Var var) This method forces to trace (to log) all modification events for the variable "var".
void	trace(Var[] vars) This method forces to trace (to log) all modification events for all variables "vars"
void	trace(Var[] vars, PropagationEvent event) This method forces solver to trace (to log) the modification "event" for all variables "var".
void	trace(Var var, PropagationEvent event) This method forces to trace (to log) the modification "event" for the variable "var".
void	trace(VarSet setVar) This method forces to trace (to log) all modification events for the variable "setVar".
void	trace(VarSet setVar, PropagationEvent event) This method forces to trace (to log) the modification "event" for the variable "setVar".

Methods inherited from class javax.constraints.impl.search.AbstractSolver

addReversibleAction, addSearchStrategy, addSearchStrategy, addSearchStrategy, addSearchStrategy, addSearchStrategy, addSearchStrategy, addSearchStrategy, addSearchStrategy, addSearchStrategy, addSolution, addStrategyLogVariables, applySolution, checkTimeLimit, clearSolutions, findOptimalSolution, findOptimalSolution, findOptimalSolution, findOptimalSolutionBasic, findOptimalSolutionDichotomize, findSolution, getMaxNumberOfSolutions, getNumberOfSolutions, getOptimizationTolerance, getProblem, getSearchStrategies, getSearchStrategy, getSolution, getSolution, getSolutions, getSolverStartTime, getStrategyLogVariables, getTimeLimit, getTimeLimitGlobal, getTimeLimitStart, isTimeLimitExceeded, isTraceExecution, isTraceSolutions, log, logStats, restoreProblem, saveProblem, setMaxNumberOfSolutions, setOptimizationTolerance, setProblem, setSearchStrategy, setSearchStrategy, setSearchStrategy, setSearchStrategy, setSearchStrategy, setSolverStartTime, setTimeLimit, setTimeLimitExceeded, setTimeLimitGlobal, setTimeLimitStart, solutionIterator, traceExecution, traceFailures, traceSolutions

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

SolverWithGoals

public SolverWithGoals(Problem problem)

Method Detail

and

public abstract Goal and(Goal g1,
                         Goal g2)

Returns an "AND" Goal. The Goal "AND" succeeds if both of the Goals "g1" and "g2" succeed. The Goal "AND" fails if at least one of the Goals "g1" or "g2" fail. It is implementation specific.

Parameters:

g1 - the first Goal which is part of the new "AND" Goal.

g2 - the other Goal which is part of the new "AND" Goal.

Returns:

a Goal "AND" between the Goals "g1" and "g2".

applySolution

public boolean applySolution(Solution solution)

This method tries to resolve the problem by applying the Solution "solution" to the problem, and returns true if "solution" satisfies all of the posted constraints, false otherwise.

Specified by:

applySolution in class AbstractSolver

Parameters:

solution - the Solution object being tested on the problem.

Returns:

true if the Solution satisfies all posted constraints, false otherwise.

backtrack

public abstract void backtrack()
                        throws java.lang.Exception

This method forces a solver to "backtrack". It is used to emulate a failure, e.g. to produce all solutions.

Throws:

java.lang.Exception

combineSearchStrategies

public Goal combineSearchStrategies()

execute

public boolean execute(Goal goal)

This methods is equivalent to execute(goal,ProblemState.DO_NOT_RESTORE);

Parameters:

goal -

Returns:

true if the goal execution succeeds or false if it fails.

execute

public abstract boolean execute(Goal goal,
                                ProblemState restoreOrNot)

findAllSolutions

public Solution[] findAllSolutions()

This method attempts to find all solutions for the Problem. It uses the default search strategy or the strategy defined by the latest method setSearchStrategy(). It returns an array of found solutions or null if there are no solutions. A user has to be careful not to overload the available memory because the number of found solutions could be huge. The process of finding all solutions can be also controlled by:

• MaxNumberOfSolutions that is the total number of considered solutions that may be limited by the method setMaxNumberOfSolutions();
• TotalTimeLimit that is the number of seconds allocated for the entire optimization process.

The common implementation is based on the SolutionIterator.

Specified by:

findAllSolutions in interface Solver

Overrides:

findAllSolutions in class AbstractSolver

Returns:

Solution[]

findOptimalSolutionDichotomize

public Solution findOptimalSolutionDichotomize(Objective objective,
                                               Var objectiveVar)

The actual minimization algorithm executes a dichotomized search. During the search it modifies an interval [objectiveMin; objectiveMax]. First it is trying to find a solution in the [objectiveMin; objectiveMid]. If it fails, it is looking at [objectiveMid+1; objectiveMax]. During this process it switches the search target: one time in looks at in the upper half of the selected interval, another time - to the lower half. Successful search stops when objectiveMax - objectiveMin <= tolerance.

Overrides:

findOptimalSolutionDichotomize in class AbstractSolver

findSolution

public Solution findSolution(ProblemState restoreOrNot)

This method attempts to find a solution of the problem, for which the solver was defined. It uses the search strategy defined by the method setSearchStrategy(). It returns the found solution (if any) or null. It also saves the solution and makes it available through the method getSolution(). If a solution is not found, the problem state is restored to that of before the invocation of this method. If a solution is found, the problem state will be restored only if the parameter "restore" is true. Otherwise all problem variables will be instantiated with the solution values. The search can be limited by time, number of failed attempts, etc.

Specified by:

findSolution in interface Solver

Specified by:

findSolution in class AbstractSolver

Parameters:

restoreOrNot - defines if the problem state should be restored after a solution is found

Returns:

a Solution if the search is successful or null

goalThis

public abstract java.lang.Object goalThis(Goal goal)

To create a new goal on the javax.constraints level without necessity to go down to the underlying CP solver, one needs to use a goal that will serve as an implementation object. "goalThis" serves exactly these purposes and actually executes the method execute() from the Goal passed as a parameter.

Parameters:

goal -

goalVarEqValue

public Goal goalVarEqValue(Var var,
                           int value)

goalVarGeValue

public Goal goalVarGeValue(Var var,
                           int value)

goalVarLeValue

public Goal goalVarLeValue(Var var,
                           int value)

goalVarNeqValue

public Goal goalVarNeqValue(Var var,
                            int value)

makeGoal

public Goal makeGoal(SearchStrategy strategy)

newSearchStrategy

public SearchStrategy newSearchStrategy()

This methods returns a new default search strategy

Specified by:

newSearchStrategy in interface Solver

Specified by:

newSearchStrategy in class AbstractSolver

Returns:

a new default search strategy

or

public abstract Goal or(Goal g1,
                        Goal g2)

Returns an "OR" Goal. The goal "OR" succeeds if at least one of the Goals "g1" or "g2" succeeds. The Goal "OR" fails if both Goals "g1" and "g2" fail. It is implementation specific.

Parameters:

g1 - the first Goal which is part of the new "OR" Goal.

g2 - the second Goal which is part of the new "OR" Goal.

Returns:

a Goal "OR" between the Goals "g1" and "g2".

trace

public void trace(Var var)

This method forces to trace (to log) all modification events for the variable "var". All modification events are described at the interface Problem

Parameters:

var -

trace

public void trace(Var[] vars)

This method forces to trace (to log) all modification events for all variables "vars"

Parameters:

vars -

trace

public void trace(Var[] vars,
                  PropagationEvent event)

This method forces solver to trace (to log) the modification "event" for all variables "var". All modification events are described at the interface Problem

Parameters:

vars -

event -

trace

public void trace(Var var,
                  PropagationEvent event)

This method forces to trace (to log) the modification "event" for the variable "var". All modification events are described at the interface Problem

Parameters:

var -

trace

public void trace(VarSet setVar)

This method forces to trace (to log) all modification events for the variable "setVar".

Parameters:

setVar -

trace

public void trace(VarSet setVar,
                  PropagationEvent event)

This method forces to trace (to log) the modification "event" for the variable "setVar". All modification events are described at the interface Problem

Parameters:

setVar -

event -