Some optimization problems, in particular column generation problems, are better described from a variable point of view instead of a constraint point of view. More...

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

Inheritance diagram for abacus::ColVar:

Public Member Functions
	ColVar (Master master, const Sub sub, bool dynamic, bool local, double lBound, double uBound, VarType::TYPE varType, double obj, int nnz, Array< int > &support, Array< double > &coeff)
	The constructor.

	ColVar (Master master, const Sub sub, bool dynamic, bool local, double lBound, double uBound, VarType::TYPE varType, double obj, SparVec &vector)
	Constructor using a sparse vector vector.

virtual	~ColVar ()

virtual double	coeff (const Constraint *con) const
	Returns the coefficient of the constraint con.

double	coeff (int i) const
	Computes the coefficient of a constraint with given index i.

Column *	column ()
	Returns a pointer to the column representing the variable.

const Column *	column () const
	Returns a const pointer to the column representing the variable.

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

Public Member Functions inherited from abacus::Variable
	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.

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 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
Column	column_

Protected Attributes inherited from abacus::Variable
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.

Friends
std::ostream &	operator<< (std::ostream &out, const ColVar &rhs)
	Output operator for column variables.

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

Some optimization problems, in particular column generation problems, are better described from a variable point of view instead of a constraint point of view.

For such context we provide the class ColVar which similar to the class RowCon stores the nonzero coefficient explicitly in an object of the class Column.

The constraint class which is associated with this variables class is the class NumCon which identifies constraints only by a unique integer number. NumCon is an abstract class.

Definition at line 56 of file colvar.h.

Constructor & Destructor Documentation

◆ ColVar() [1/2]

abacus::ColVar::ColVar	(	Master *	master,
		const Sub *	sub,
		bool	dynamic,
		bool	local,
		double	lBound,
		double	uBound,
		VarType::TYPE	varType,
		double	obj,
		int	nnz,
		Array< int > &	support,
		Array< double > &	coeff
	)

inline

The constructor.

Parameters

master	A pointer to the corresponding master of the optimization.
sub	A pointer to the subproblem associated with the variable. This can be also the 0-pointer.
dynamic	If this argument is true, then the variable can be removed from the active variable set during the subproblem optimization.
local	If this argument is true, then the constraint is considered to be only locally valid. As a local variable is associated with a subproblem, sub must not be 0 if local is true.
lBound	The lower bound of the variable.
uBound	The upper bound of the variable.
varType	The type of the variable.
obj	The objective function coefficient of the variable.
nnz	The number of nonzero elements of the variable.
support	The array storing the constraints with the nonzero coefficients.
coeff	The nonzero coefficients of the constraints stored in support.

Definition at line 77 of file colvar.h.

◆ ColVar() [2/2]

abacus::ColVar::ColVar	(	Master *	master,
		const Sub *	sub,
		bool	dynamic,
		bool	local,
		double	lBound,
		double	uBound,
		VarType::TYPE	varType,
		double	obj,
		SparVec &	vector
	)

inline

Constructor using a sparse vector vector.

Parameters

master	A pointer to the corresponding master of the optimization.
sub	A pointer to the subproblem associated with the variable. This can be also the 0-pointer.
dynamic	If this argument is true, then the variable can be removed from the active variable set during the subproblem optimization.
local	If this argument is true, then the constraint is considered to be only locally valid. As a local variable is associated with a subproblem, sub must not be 0 if local is true.
lBound	The lower bound of the variable.
uBound	The upper bound of the variable.
varType	The type of the variable.
obj	The objective function coefficient of the variable.
vector	The constraints.

Definition at line 109 of file colvar.h.

◆ ~ColVar()

virtual abacus::ColVar::~ColVar ( )

inlinevirtual

Definition at line 123 of file colvar.h.

Member Function Documentation

◆ coeff() [1/2]

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

inlinevirtual

Returns the coefficient of the constraint con.

Parameters

con	The constraint of which the coefficient is computed. This must be a pointer to the class NumCon.

Reimplemented from abacus::Variable.

Definition at line 152 of file colvar.h.

◆ coeff() [2/2]

double abacus::ColVar::coeff ( int i ) const

inline

Computes the coefficient of a constraint with given index i.

Parameters

i	The number of the constraint.

Returns: The coefficient of constraint i.

Definition at line 162 of file colvar.h.

◆ column() [1/2]

Column * abacus::ColVar::column ( )

inline

Returns a pointer to the column representing the variable.

Definition at line 166 of file colvar.h.

◆ column() [2/2]

const Column * abacus::ColVar::column ( ) const

inline

Returns a const pointer to the column representing the variable.

Definition at line 169 of file colvar.h.

◆ print()

virtual void abacus::ColVar::print ( std::ostream & out ) const

inlinevirtual

Writes the column representing the variable to output stream out.

It redefines the virtual function print() of the base class ConVar.

Parameters

out	The output stream.

Reimplemented from abacus::ConVar.

Definition at line 143 of file colvar.h.

Friends And Related Symbol Documentation

◆ operator<<

std::ostream & operator<<	(	std::ostream &	out,
		const ColVar &	rhs
	)

friend

Output operator for column variables.

The output operator writes the column representing the variable to an output stream.

Parameters

out	The output stream.
rhs	The variable being output.

Returns: A reference to the output stream.

Definition at line 177 of file colvar.h.

Member Data Documentation

◆ column_

Column abacus::ColVar::column_

protected

Definition at line 173 of file colvar.h.

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

include/ogdf/lib/abacus/colvar.h

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Public Member Functions

Protected Attributes

Friends

Additional Inherited Members

Detailed Description

Constructor & Destructor Documentation

◆ ColVar() [1/2]

◆ ColVar() [2/2]

◆ ~ColVar()

Member Function Documentation

◆ coeff() [1/2]

◆ coeff() [2/2]

◆ column() [1/2]

◆ column() [2/2]

◆ print()

Friends And Related Symbol Documentation

◆ operator<<

Member Data Documentation

◆ column_

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