#include <Presolver.h>

Collaboration diagram for Minotaur::Presolver:

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Public Member Functions
	Presolver ()
	Default constructor.

	Presolver (ProblemPtr problem, EnvPtr env, HandlerVector handlers)
	Constructor for a given problem.

virtual	~Presolver ()
	Destroy.

virtual void	presolve ()
	Default presolve.

virtual SolutionPtr	getSolution ()
	get solution if any

virtual SolveStatus	getStatus ()

virtual void	standardize ()

virtual SolveStatus	solve ()

virtual void	removeDuplicates ()
	Search and remove any duplicate rows and columns from the problem.

virtual void	getX (const double x, DoubleVector newx)

SolutionPtr	getPostSol (SolutionPtr s)

Protected Member Functions
void	removeEmptyObj_ ()
	Remove objective function, if it is zero or constant.

void	minimizify_ ()
	convert to minimization problem.

void	linearizeObjective_ ()

void	ifIntsAreBins_ ()

void	standardizeConstraints_ ()

Protected Attributes
EnvPtr	env_
	Environment.

double	eTol_
	Tolerance for checking feasibility.

HandlerVector	handlers_
	Handlers used to presolve the problem.

double	intTol_
	A value in [z-intTol_, z+intTol_], z integer, will be treated as z.

LoggerPtr	logger_
	Log manager.

PreModQ	mods_
	A queue of presolve-modifications required for post-solve.

ProblemPtr	problem_

SolutionPtr	sol_
	Pointer to optimal solution, if one found.

SolveStatus	status_
	Status.

Static Protected Attributes
static const std::string	me_ = "Presolver: "
	For logging.

Detailed Description

A Presolver is used to modify a problem such that it becomes simplified or easier to solve. A Presolver, in its default form, will create a copy of the problem. A user will need to specifically tell presolver not to copy a problem. It should maintain a list of changes made to the original problem.

The Presolver may also be able to detect infeasibility, optimality, feasibility or unboundedness. A presolver in this way, is very much a solver.

Member Function Documentation

◆ getPostSol()

SolutionPtr Presolver::getPostSol ( SolutionPtr s )

Construct a solution for the original problem from that of the presolved problem.

◆ getX()

void Presolver::getX	(	const double *	x,
		DoubleVector *	newx
	)

virtual

Translate a given x into solution of the original problem. The space for newx needs to be allocated.

◆ ifIntsAreBins_()

void Presolver::ifIntsAreBins_ ( )

protected

Some interfaces (like AMPL) and the users may specify binary variables as integer variables. This function converts such variables to binary.

◆ linearizeObjective_()

void Presolver::linearizeObjective_ ( )

protected

Replace the objective with a linear function. The problem remains equivalent to the one before the function is called.

◆ standardize()

void Presolver::standardize ( )

virtual

standardize is called before solving any problem even when presolve is disabled. This method is necessary to standardize the problem: convert maximize to minimize, add a new variable for the objective function, ...

The documentation for this class was generated from the following files:

/home/amahajan/tmp/minotaur-test/src/base/Presolver.h
/home/amahajan/tmp/minotaur-test/src/base/Presolver.cpp

Public Member Functions

Protected Member Functions

Protected Attributes