Package org.tweetyproject.lp.asp.reasoner

Class ClingoSolver

java.lang.Object

org.tweetyproject.lp.asp.reasoner.ASPSolver

org.tweetyproject.lp.asp.reasoner.ClingoSolver

All Implemented Interfaces:

ModelProvider<ASPRule,Program,AnswerSet>, QualitativeReasoner<Program,ASPLiteral>, Reasoner<Boolean,Program,ASPLiteral>

public class ClingoSolver
extends ASPSolver

Invokes Clingo (Part of the Potassco project), an ASP system that grounds and solves logic programs, and returns computed answer sets.

Author:

Nils Geilen, Matthias Thimm, Anna Gessler

Constructor Summary

Constructors

Constructor	Description
ClingoSolver(String pathToClingo)	Constructs a new instance pointing to a specific Clingo solver.
ClingoSolver(String pathToClingo, int maxNOfModels)	Constructs a new instance pointing to a specific Clingo solver.
ClingoSolver(String pathToClingo, Shell bash)	Constructs a new instance pointing to a specific Clingo solver.

Method Summary

Modifier and Type	Method	Description
AnswerSet	getModel(Program p)	Returns a single (dedicated) model of the given belief base.
List<AnswerSet>	getModels(File file)	Returns a characterizing model (answer set) of the given belief base.
List<AnswerSet>	getModels(String s)	Returns a characterizing model (answer set) of the given belief base.
List<AnswerSet>	getModels(Program p)	Returns a characterizing model of the given belief base
List<Integer>	getOptimum(String p)
List<Integer>	getOptimum(Program p)	Computes the optimum of a program that contains optimization statements, if there is one.
String	getOptimumString()	Returns the optimum of the previously solved program, if there is one.
boolean	isInstalled()	Checks whether the underlying solver or reasoning mechanism used by this reasoner is installed and available for use.
Boolean	query(Program beliefbase, ASPLiteral formula)	Queries the given belief base with the provided formula and returns a boolean result.
Boolean	query(Program beliefbase, ASPLiteral formula, InferenceMode inferenceMode)	Evaluates a query on the given belief base using the specified inference mode.
void	setOptions(String options)	Set the command line options for Clingo.
void	setPathToClingo(String path)	Sets the location of the Clingo solver on the hard drive.
void	toggleOutputWhitelist(boolean b)	Activates or deactivates the option to use a whitelist of predicates.

Methods inherited from class org.tweetyproject.lp.asp.reasoner.ASPSolver

getIntegerMaximum, getMaxNumOfModels, getModel, getModels, getOutput, setIntegerMaximum, setMaxNumOfModels

Methods inherited from class java.lang.Object

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

Constructor Details

ClingoSolver

public ClingoSolver(String pathToClingo,
 Shell bash)

Constructs a new instance pointing to a specific Clingo solver. The maximum number of models that Clingo will compute is set to the default value (see ASPSolver.maxNumOfModels).

Parameters:

pathToClingo - binary location of Clingo on the hard drive. The given location has to contain a binary called "clingo". Do not include the binary itself in the path.

bash - shell to run commands

ClingoSolver

public ClingoSolver(String pathToClingo)

Constructs a new instance pointing to a specific Clingo solver. The maximum number of models that Clingo will compute is set to the default value (see ASPSolver.maxNumOfModels).

Parameters:

pathToClingo - binary location of Clingo on the hard drive. The given location has to contain a binary called "clingo". Do not include the binary itself in the path.

ClingoSolver

public ClingoSolver(String pathToClingo,
 int maxNOfModels)

Constructs a new instance pointing to a specific Clingo solver.

Parameters:

pathToClingo - binary location of Clingo on the hard drive. The given location has to contain a binary called "clingo". Do not include the binary itself in the path.

maxNOfModels - the maximum number of models that Clingo will compute. Set it to 0 if you want all models.

Method Details

getOptimumString

public String getOptimumString()
                        throws SolverException

Returns the optimum of the previously solved program, if there is one.

Returns:

optimum of previously solved program in string format, i.e. numbers separated by spaces

Throws:

SolverException - SolverException

getOptimum

public List<Integer> getOptimum(String p)

Parameters:

p - problem to be solved

Returns:

optima

getModel

public AnswerSet getModel(Program p)

Description copied from interface: ModelProvider

Returns a single (dedicated) model of the given belief base. If the implemented method allows for more than one dedicated model, the selection may be non-deterministic.

Parameters:

p - some belief base

Returns:

a selected model of the belief base.

getModels

public List<AnswerSet> getModels(Program p)

Description copied from interface: ModelProvider

Returns a characterizing model of the given belief base

Specified by:

getModels in interface ModelProvider<ASPRule,Program,AnswerSet>

Specified by:

getModels in class ASPSolver

Parameters:

p - some belief base

Returns:

the (selected) models of the belief base

getModels

public List<AnswerSet> getModels(String s)

Description copied from class: ASPSolver

Returns a characterizing model (answer set) of the given belief base.

Specified by:

getModels in class ASPSolver

Parameters:

s - containing belief base

Returns:

AnswerSet

getModels

public List<AnswerSet> getModels(File file)

Description copied from class: ASPSolver

Returns a characterizing model (answer set) of the given belief base.

Specified by:

getModels in class ASPSolver

Parameters:

file - containing belief base

Returns:

AnswerSet

getOptimum

public List<Integer> getOptimum(Program p)

Computes the optimum of a program that contains optimization statements, if there is one. Note: This methods calculates only the optimum and returns no answer sets.

Parameters:

p - ASP program

Returns:

list of calculated optima

query

public Boolean query(Program beliefbase,
 ASPLiteral formula)

Description copied from interface: QualitativeReasoner

Queries the given belief base with the provided formula and returns a boolean result. The result indicates whether the formula is entailed or satisfied by the belief base according to the qualitative reasoning method implemented by the reasoner.

Specified by:

query in interface QualitativeReasoner<Program,ASPLiteral>

Specified by:

query in interface Reasoner<Boolean,Program,ASPLiteral>

Specified by:

query in class ASPSolver

Parameters:

beliefbase - The belief base to be queried.

formula - The formula for which the query is made.

Returns:

`TRUE` if the formula is entailed or satisfied by the belief base, `FALSE` otherwise.

query

public Boolean query(Program beliefbase,
 ASPLiteral formula,
 InferenceMode inferenceMode)

Evaluates a query on the given belief base using the specified inference mode.

This method checks whether the given formula is entailed by the belief base under the specified inference mode. It retrieves the answer sets of the belief base and checks the presence of the formula in these sets based on the chosen inference mode, either skeptical or credulous.

Parameters:

beliefbase - The program representing the belief base to query.

formula - The formula (literal) to be checked within the answer sets.

inferenceMode - The mode of inference, either skeptical or credulous.

Returns:

true if the formula is entailed by the belief base under the specified inference mode, false otherwise.

toggleOutputWhitelist

public void toggleOutputWhitelist(boolean b)

Activates or deactivates the option to use a whitelist of predicates. If activated, answer sets will only contain atoms over predicates that are part of the whitelist. This corresponds to the #show statement of the clingo input language.

Parameters:

b - whether to use a whitelist of predicate

setOptions

public void setOptions(String options)

Set the command line options for Clingo.

Parameters:

options - a string of options in the correct format, e.g. in the form "--opt" and separated by spaces

setPathToClingo

public void setPathToClingo(String path)

Sets the location of the Clingo solver on the hard drive.

Parameters:

path - path to Clingo

isInstalled

public boolean isInstalled()

Description copied from interface: QualitativeReasoner

Checks whether the underlying solver or reasoning mechanism used by this reasoner is installed and available for use. This can be helpful when the reasoner depends on external tools or libraries for performing the reasoning tasks.

Returns:

`true` if the solver is installed and available, `false` otherwise.