Forms the virtual base class for all possible variables given in pool format. More...

#include <ogdf/lib/abacus/variable.h>

Inheritance diagram for abacus::Variable:

Public Member Functions
	Variable (Master master, const Sub sub, bool dynamic, bool local, double obj, double lBound, double uBound, VarType::TYPE type)
	Initializes a variable.

virtual	~Variable ()

bool	binary () const
	Returns true If the type of the variable is Binary, false otherwise.

virtual double	coeff (const Constraint *con) const
	Computes the coefficient of the variable in the constraint con.

bool	discrete () const
	Returns true if the type of the variable is Integer or Binary, false otherwise.

FSVarStat *	fsVarStat ()

const FSVarStat *	fsVarStat () const

virtual int	genColumn (Active< Constraint, Variable > *actCon, Column &col) const
	Computes the column col of the variable associated with the active constraints *actCon.

bool	integer () const
	Returns true If the type of the variable is Integer, false otherwise.

double	lBound () const
	Returns the lower bound of the variable.

void	lBound (double newBound)
	Sets the lower bound of the variable to newBound.

virtual double	obj () const
	Returns the objective function coefficient.

void	printCol (std::ostream &out, Active< Constraint, Variable > *constraints) const
	Writes the column of the variable corresponding to the constraints to output stream out.

virtual double	redCost (Active< Constraint, Variable > actCon, double y) const
	Computes the reduced cost of the variable corresponding the constraint set actCon and the dual variables y.

double	uBound () const
	Returns the upper bound of the variable.

void	uBound (double newBound)
	Sets the upper bound of the variable to newBound.

virtual bool	useful (Active< Constraint, Variable > actCon, double y, double lpVal) const
	Returns whether an (inactive) discrete variable is useful.

virtual bool	valid (const Sub *sub) const
	Returns true if the variable is valid, false otherwise.

VarType::TYPE	varType () const
	Returns the type of the variable.

virtual bool	violated (Active< Constraint, Variable > constraints, double y, double *slack=nullptr) const
	Checks, if a variable does not price out correctly.

virtual bool	violated (double rc) const
	Checks, if a variable does not price out correctly.

Public Member Functions inherited from abacus::ConVar
	ConVar (Master master, const Sub sub, bool dynamic, bool local)
	Creates an instance of type ConVar.

virtual	~ConVar ()

bool	active () const
	Checks if the constraint/variable is active in at least one active subproblem.

virtual bool	dynamic () const
	Return true if the constraint/variable is dynamic.

virtual bool	equal (const ConVar *cv) const
	Should compare if the constraint/variable is identical (in a mathematical sense) with the constraint/variable cv.

bool	global () const
	Returns true if the constraint/variable is globally valid, false otherwise.

virtual unsigned	hashKey () const
	Should provide a key for the constraint/variable that can be used to insert it into a hash table.

bool	local () const
	Returns true if the constraint/variable is only locally valid, false otherwise.

virtual const char *	name () const
	Should return the name of the constraint/variable.

virtual void	print (std::ostream &out) const
	Writes the constraint/variable to the output stream out.

virtual double	rank () const
	The function should return a rank associated with the constraint/variable.

const Sub *	sub () const
	Returns a const pointer to the subproblem associated with the constraint/variable.

void	sub (Sub *sub)
	Associates a new subproblem with the constraint/variable.

bool	expanded () const
	Returns true if the expanded format of a constraint/variable is available, false otherwise.

virtual void	expand () const
	Expands a constraint/variable.

virtual void	compress () const
	Compresses a constraint/variable.

virtual bool	deletable () const
	Returns true if the constraint/variable can be destructed.

Public Member Functions inherited from abacus::AbacusRoot
virtual	~AbacusRoot ()
	The destructor.

Protected Attributes
FSVarStat	fsVarStat_
	The global status of fixing and setting of the variable.

double	lBound_
	The lower bound of the variable.

double	obj_
	The objective function coefficient of the variable.

VarType	type_
	The type of the variable.

double	uBound_
	The upper bound of the variable.

Protected Attributes inherited from abacus::ConVar
bool	dynamic_
	If this member is true then the constraint/variable can be also removed from the active formulation after it is added the first time.

bool	expanded_
	true, if expanded version of constraint/variables available.

bool	local_
	true if the constraint/variable is only locally valid

Master *	master_
	A pointer to the corresponding master of the optimization.

int	nActive_
	The number of active subproblems of which the constraint/variable belongs to the set of active constraints/variables.

int	nLocks_
	The number of locks which have been set on the constraint/variable.

int	nReferences_
	The number of references to the pool slot the constraint is stored in.

const Sub *	sub_
	A pointer to the subproblem associated with the constraint/variable.

Additional Inherited Members
Static Public Member Functions inherited from abacus::AbacusRoot
static bool	ascii2bool (const string &str)
	Converts the string str to a boolean value.

static bool	endsWith (const string &str, const string &end)
	Returns true if str ends with end, false otherwise.

static double	fracPart (double x)
	Returns the absolute value of the fractional part of x.

static const char *	onOff (bool value)
	Converts a boolean variable to the strings "on" and "off".

Detailed Description

Forms the virtual base class for all possible variables given in pool format.

Variables are one of the central items in a linear-programming based branch-and-bound algorithm. This class forms the virtual base class for all possible variables given in pool format and is derived from the common base class ConVar of all constraints and variables.

Definition at line 59 of file variable.h.

Constructor & Destructor Documentation

◆ Variable()

abacus::Variable::Variable	(	Master *	master,
		const Sub *	sub,
		bool	dynamic,
		bool	local,
		double	obj,
		double	lBound,
		double	uBound,
		VarType::TYPE	type
	)

inline

Initializes a variable.

Parameters

master	A pointer to the corresponding master of the optimization.
sub	A pointer to the subproblem associated with the variable. This can also be the 0-pointer.
dynamic	If this argument is true, then the variable can also be removed again from the set of active variables after it is added once.
local	If this argument is true, then the variable is only locally valid, otherwise it is globally valid. As a locally valid variable is always associated with a subproblem, the argument sub must not be 0 if local is true.
obj	The objective function coefficient.
lBound	The lower bound of the variable.
uBound	The upper bound of the variable.
type	The type of the variable.

Definition at line 78 of file variable.h.

◆ ~Variable()

virtual abacus::Variable::~Variable ( )

inlinevirtual

Definition at line 92 of file variable.h.

Member Function Documentation

◆ binary()

bool abacus::Variable::binary ( ) const

inline

Returns true If the type of the variable is Binary, false otherwise.

Definition at line 104 of file variable.h.

◆ coeff()

virtual double abacus::Variable::coeff ( const Constraint * con ) const

inlinevirtual

Computes the coefficient of the variable in the constraint con.

Per default the coefficient of a variable iscomputed indirectly via the coefficient of a constraint. Problem specific redefinitions might be required.

Parameters

con	The constraint of which the coefficient should be computed.

Returns: The coefficient of the variable in the constraint con.

Reimplemented in abacus::ColVar.

Definition at line 188 of file variable.h.

◆ discrete()

bool abacus::Variable::discrete ( ) const

inline

Returns true if the type of the variable is Integer or Binary, false otherwise.

Definition at line 100 of file variable.h.

◆ fsVarStat() [1/2]

FSVarStat * abacus::Variable::fsVarStat ( )

inline

Note: This is the global status of fixing/setting that might differ from the local status of fixing/setting a variable returned by the function Sub::fsVarStat().

Returns: A pointer to the global status of fixing and setting of the variable.

Definition at line 144 of file variable.h.

◆ fsVarStat() [2/2]

const FSVarStat * abacus::Variable::fsVarStat ( ) const

inline

Note: This is the global status of fixing/setting that might differ from the local status of fixing/setting a variable returned by the function Sub::fsVarStat().

Returns: A const pointer to the global status of fixing and setting of the variable.

Definition at line 153 of file variable.h.

◆ genColumn()

virtual int abacus::Variable::genColumn	(	Active< Constraint, Variable > *	actCon,
		Column &	col
	)		const

virtual

Computes the column col of the variable associated with the active constraints *actCon.

Note: The upper and lower bound of the column are initialized with the global upper and lower bound of the variable. Therefore, an adaption with the local bounds might be required.

Parameters

actCon	The constraints for which the column of the variable should be computed.
col	Stores the column when the function terminates.

Returns: The number of nonzero entries in col.

◆ integer()

bool abacus::Variable::integer ( ) const

inline

Returns true If the type of the variable is Integer, false otherwise.

Definition at line 108 of file variable.h.

◆ lBound() [1/2]

double abacus::Variable::lBound ( ) const

inline

Returns the lower bound of the variable.

Definition at line 127 of file variable.h.

◆ lBound() [2/2]

void abacus::Variable::lBound ( double newBound )

inline

Sets the lower bound of the variable to newBound.

Parameters

newBound The new value of the lower bound.

Definition at line 134 of file variable.h.

◆ obj()

virtual double abacus::Variable::obj ( ) const

inlinevirtual

Returns the objective function coefficient.

Definition at line 112 of file variable.h.

◆ printCol()

void abacus::Variable::printCol	(	std::ostream &	out,
		Active< Constraint, Variable > *	constraints
	)		const

Writes the column of the variable corresponding to the constraints to output stream out.

Parameters

out	The output stream.
constraints	The constraints for which the column should be written.

◆ redCost()

virtual double abacus::Variable::redCost	(	Active< Constraint, Variable > *	actCon,
		double *	y
	)		const

virtual

Computes the reduced cost of the variable corresponding the constraint set actCon and the dual variables y.

Given the dual variables \(y\), then the reduced cost of a variable with objective function coefficient \(c_e\), column \(a_{.e}\) are defined as \(c_e - y^{\mathrm{T}} a_{.e}\).

Parameters

actCon	The constraints associated with the dual variables y.
y	The dual variables of the constraint.

Returns: The reduced cost of the variable.

◆ uBound() [1/2]

double abacus::Variable::uBound ( ) const

inline

Returns the upper bound of the variable.

Definition at line 116 of file variable.h.

◆ uBound() [2/2]

void abacus::Variable::uBound ( double newBound )

inline

Sets the upper bound of the variable to newBound.

Parameters

newBound The new value of the upper bound.

Definition at line 123 of file variable.h.

◆ useful()

virtual bool abacus::Variable::useful	(	Active< Constraint, Variable > *	actCon,
		double *	y,
		double	lpVal
	)		const

virtual

Returns whether an (inactive) discrete variable is useful.

An (inactive) discrete variable is considered as useful() if its activation might not produce only solutions worse than the best known feasible solution.

This is the same criterion for fixing inactive variables by reduced cost criteria.

Parameters

actCon	The active constraints.
y	The dual variables of these constraints.
lpVal	The value of the linear program.

Returns: true If the variable is considered as useful, false otherwise.

◆ valid()

bool abacus::Variable::valid ( const Sub * sub ) const

inlinevirtual

Returns true if the variable is valid, false otherwise.

Returns: true If the variable is globally valid, or the subproblem sub is an ancestor in the enumeration tree of the subproblem associated with the variable.; false otherwise.

Parameters

sub	The subproblem for which validity of the variable is checked.

Definition at line 270 of file variable.h.

◆ varType()

VarType::TYPE abacus::Variable::varType ( ) const

inline

Returns the type of the variable.

Definition at line 96 of file variable.h.

◆ violated() [1/2]

virtual bool abacus::Variable::violated	(	Active< Constraint, Variable > *	constraints,
		double *	y,
		double *	slack = `nullptr`
	)		const

virtual

Checks, if a variable does not price out correctly.

I.e., if the reduced cost of the variable associated with the constraint set constraints and the dual variables y are positive for a maximization problem and negative for a minimization problem, respectively.

Parameters

constraints	The constraints associated with the dual variables y.
y	The dual variables of the constraint.
slack	If r is not the 0-pointer, it will store the reduced cost after the function call. Per default r is 0.

Returns: true if the variable does not price out correctly, false otherwise.

◆ violated() [2/2]

virtual bool abacus::Variable::violated ( double rc ) const

virtual

Checks, if a variable does not price out correctly.

I.e., if the reduced cost rc is positive fora maximization problem and negative for a minimization problem, respectively.

Parameters

rc	The reduced cost of the variable.

Returns: true If the variable does not price out correctly, false otherwise.

Member Data Documentation

◆ fsVarStat_

FSVarStat abacus::Variable::fsVarStat_

protected

The global status of fixing and setting of the variable.

Definition at line 263 of file variable.h.

◆ lBound_

double abacus::Variable::lBound_

protected

The lower bound of the variable.

Definition at line 265 of file variable.h.

◆ obj_

double abacus::Variable::obj_

protected

The objective function coefficient of the variable.

Definition at line 264 of file variable.h.

◆ type_

VarType abacus::Variable::type_

protected

The type of the variable.

Definition at line 267 of file variable.h.

◆ uBound_

double abacus::Variable::uBound_

protected

The upper bound of the variable.

Definition at line 266 of file variable.h.

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

include/ogdf/lib/abacus/variable.h

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Public Member Functions

Protected Attributes

Additional Inherited Members

Detailed Description

Constructor & Destructor Documentation

◆ Variable()

◆ ~Variable()

Member Function Documentation

◆ binary()

◆ coeff()

◆ discrete()

◆ fsVarStat() [1/2]

◆ fsVarStat() [2/2]

◆ genColumn()

◆ integer()

◆ lBound() [1/2]

◆ lBound() [2/2]

◆ obj()

◆ printCol()

◆ redCost()

◆ uBound() [1/2]

◆ uBound() [2/2]

◆ useful()

◆ valid()

◆ varType()

◆ violated() [1/2]

◆ violated() [2/2]

Member Data Documentation

◆ fsVarStat_

◆ lBound_

◆ obj_

◆ type_

◆ uBound_

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