Package org.tweetyproject.math.opt.solver

Class GurobiOptimizer

java.lang.Object

org.tweetyproject.math.opt.solver.Solver

org.tweetyproject.math.opt.solver.GurobiOptimizer

public class GurobiOptimizer
extends Solver

This class is a wrapper for the Gurobi optimizer (https://www.gurobi.com). Works with Gurobi 9.1.0

Author:

Sebastian Franke, Matthias Thimm

Constructor Summary

Constructors

Constructor	Description
GurobiOptimizer()	Constructor

Method Summary

Modifier and Type	Method	Description
void	addStatementToGurobi(Statement s, Integer i)	parses a statement into a gurobi constrant and adds it to the model
static boolean	isInstalled()	Return if solver is installed
gurobi.GRBExpr	parseTerm(Term term)	parses a term from tweety to GRB the input term needs to be linear or quadratic
void	parseVars(OptimizationProblem prob)	takes all Variables from a tweety problem and maps them to GRB Varaibles
Map<Variable,Term>	solve(GeneralConstraintSatisfactionProblem problem)	Computes a solution to the given constraint satisfaction or optimization problem, i.e.
Map<Variable,Term>	solve(Term t, int optimization_type)	Returns the variable assignment that maximizes/minimizes the given term (which only contains variables with defined upper and lower bounds).
ArrayList<Sum>	toQuadraticFormHelper(Term sum)	Return a list of products from a quadratic term in normal form

Methods inherited from class org.tweetyproject.math.opt.solver.Solver

getDefaultGeneralSolver, getDefaultIntegerLinearSolver, getDefaultLinearSolver, hasDefaultGeneralSolver, hasDefaultIntegerLinearSolver, hasDefaultLinearSolver, setDefaultGeneralSolver, setDefaultIntegerLinearSolver, setDefaultLinearSolver

Methods inherited from class java.lang.Object

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

Constructor Details

GurobiOptimizer

public GurobiOptimizer()
                throws gurobi.GRBException

Constructor

Throws:

gurobi.GRBException - GRBException

Method Details

parseVars

public void parseVars(OptimizationProblem prob)
               throws gurobi.GRBException

takes all Variables from a tweety problem and maps them to GRB Varaibles

Parameters:

prob - problem

Throws:

gurobi.GRBException - GRBException

parseTerm

public gurobi.GRBExpr parseTerm(Term term)

parses a term from tweety to GRB the input term needs to be linear or quadratic

Parameters:

term - term

Returns:

gurobi expression

addStatementToGurobi

public void addStatementToGurobi(Statement s,
 Integer i)
                          throws gurobi.GRBException

parses a statement into a gurobi constrant and adds it to the model

Parameters:

s - statement to be added

i - running number of the constraint to be put into the Gurobi name of the constraint

Throws:

gurobi.GRBException - GRBException

solve

public Map<Variable,Term> solve(GeneralConstraintSatisfactionProblem problem)
                         throws GeneralMathException

Description copied from class: Solver

Computes a solution to the given constraint satisfaction or optimization problem, i.e. a mapping from variables of the problem to terms.

Specified by:

solve in class Solver

Parameters:

problem - the actual problem

Returns:

a mapping from variables of the problem to terms.

Throws:

GeneralMathException - if something went wrong.

solve

public Map<Variable,Term> solve(Term t,
 int optimization_type)
                         throws GeneralMathException,
gurobi.GRBException

Returns the variable assignment that maximizes/minimizes the given term (which only contains variables with defined upper and lower bounds).

Parameters:

t - the term to be evaluated

optimization_type - one of OptimizationProblem.MAXIMIZE, OptimizationProblem.MINIMIZE

Returns:

the optimal variable assignment

Throws:

GeneralMathException - if there is some issue in the computation

gurobi.GRBException - GRBException

toQuadraticFormHelper

public ArrayList<Sum> toQuadraticFormHelper(Term sum)

Return a list of products from a quadratic term in normal form

Parameters:

sum - a quadratic term in normal form

Returns:

a list of products from a quadratic term in normal form

isInstalled

public static boolean isInstalled()
                           throws UnsupportedOperationException

Return if solver is installed

Returns:

if solver is installed

Throws:

UnsupportedOperationException - UnsupportedOperationException