#include <IntVarHandler.h>

Inheritance diagram for Minotaur::IntVarHandler:

Collaboration diagram for Minotaur::IntVarHandler:

Public Member Functions
	IntVarHandler ()
	Default constructor.

	IntVarHandler (EnvPtr env, ProblemPtr problem)
	Constructor.

	~IntVarHandler ()
	Destroy.

Branches	getBranches (BrCandPtr cand, DoubleVector &x, RelaxationPtr rel, SolutionPoolPtr s_pool)
	Return branches for branching. More...

void	getBranchingCandidates (RelaxationPtr rel, const DoubleVector &x, ModVector &mods, BrVarCandSet &cands, BrCandVector &gencands, bool &is_inf)
	find branching candidates. More...

ModificationPtr	getBrMod (BrCandPtr cand, DoubleVector &x, RelaxationPtr rel, BranchDirection dir)
	Get the modifcation that creates a given (up or down) branch. More...

double	getTol () const
	Return the integer tolerance.

std::string	getName () const
	Return the name of the handler. More...

bool	isFeasible (ConstSolutionPtr sol, RelaxationPtr relaxation, bool &should_prune, double &inf_meas)
	Check if a solution is feasible. More...

bool	isNeeded ()
	Return true if this handler is needed for the problem. More...

void	postsolveGetX (const double , UInt, DoubleVector )
	Does nothing.

SolveStatus	presolve (PreModQ , bool , Solution **)
	Presolve. Don't do anything. More...

bool	presolveNode (RelaxationPtr, NodePtr, SolutionPoolPtr, ModVector &, ModVector &)
	Does nothing. More...

void	relaxInitFull (RelaxationPtr rel, SolutionPool sp, bool is_inf)
	Create root relaxation if doing full node relaxations. More...

void	relaxInitInc (RelaxationPtr rel, SolutionPool sp, bool is_inf)
	Create root relaxation if doing incremental node relaxations. More...

void	relaxNodeFull (NodePtr node, RelaxationPtr rel, bool *is_inf)
	Create a relaxation for a node, building from scratch. More...

void	relaxNodeInc (NodePtr node, RelaxationPtr rel, bool *is_inf)
	Create an incremental relaxation for a node. More...

void	separate (ConstSolutionPtr, NodePtr, RelaxationPtr, CutManager , SolutionPoolPtr, ModVector &, ModVector &, bool , SeparationStatus *)

void	setTol (double tol)
	Set the integer tolerance.

void	writePreStats (std::ostream &) const
	Does nothing.

Public Member Functions inherited from Minotaur::Handler
	Handler ()
	Default constructor.

virtual	~Handler ()
	Destroy.

virtual void	addConstraint (ConstraintPtr newcon)
	Add constraint to be handled by this handler. More...

virtual ConstraintVector::const_iterator	consBegin () const

virtual ConstraintVector::const_iterator	consEnd () const

virtual int	fixNodeErr (RelaxationPtr, ConstSolutionPtr, SolutionPoolPtr, bool &)

virtual Branches	getBranches (BrCandPtr cand, DoubleVector &x, RelaxationPtr rel, SolutionPoolPtr s_pool)=0
	Return branches for branching. More...

virtual void	getBranchingCandidates (RelaxationPtr rel, const DoubleVector &x, ModVector &mods, BrVarCandSet &cands, BrCandVector &gencands, bool &is_inf)=0
	find branching candidates. More...

virtual ModificationPtr	getBrMod (BrCandPtr cand, DoubleVector &x, RelaxationPtr rel, BranchDirection dir)=0
	Get the modifcation that creates a given (up or down) branch. More...

virtual std::string	getName () const =0
	Return the name of the handler. More...

bool	getStrongerMods (RelaxationPtr rel, NodePtr node, SolutionPoolPtr s_pool, ModVector &p_mods, ModVector &r_mods)
	do node presolve to get mods for stronger branching All params are presolveNode params.

virtual bool	isFeasible (ConstSolutionPtr sol, RelaxationPtr rel, bool &should_prune, double &inf_meas)=0
	Check if a solution is feasible. More...

virtual bool	isNeeded ()
	Return true if this handler is needed for the problem. More...

virtual SolveStatus	presolve (PreModQ pre_mods, bool changed, Solution **sol)=0
	Initial presolve. More...

virtual bool	presolveNode (RelaxationPtr rel, NodePtr node, SolutionPoolPtr s_pool, ModVector &p_mods, ModVector &r_mods)=0
	Presolve the problem and its relaxation at a node. More...

virtual bool	postSolveRootNode (RelaxationPtr, SolutionPoolPtr, ConstSolutionPtr, ModVector &, ModVector &)
	At the root node post solve the problem and its relaxation. LP based bound tightening (OBBT) is employed here after filtering variables for which no OBBT is required. More...

virtual void	relaxInitFull (RelaxationPtr rel, SolutionPool sp, bool is_inf)=0
	Create root relaxation if doing full node relaxations. More...

virtual void	relaxInitInc (RelaxationPtr rel, SolutionPool sp, bool is_inf)=0
	Create root relaxation if doing incremental node relaxations. More...

virtual void	relaxNodeFull (NodePtr node, RelaxationPtr rel, bool *is_inf)=0
	Create a relaxation for a node, building from scratch. More...

virtual void	relaxNodeInc (NodePtr node, RelaxationPtr rel, bool *is_inf)=0
	Create an incremental relaxation for a node. More...

virtual void	removeCuts (RelaxationPtr, ConstSolutionPtr)

virtual void	separate (ConstSolutionPtr sol, NodePtr node, RelaxationPtr rel, CutManager cutman, SolutionPoolPtr s_pool, ModVector &p_mods, ModVector &r_mods, bool sol_found, SeparationStatus *status)=0
	add cuts to separate a given point. More...

virtual void	setModFlags (bool mod_prob, bool mod_rel)
	Tell the handler whether the problem will be modified or the relaxation will be modified or both. These modifications will be saved in the tree as well. More...

virtual void	simplePresolve (ProblemPtr, SolutionPoolPtr, ModVector &, SolveStatus &status)

void	undoStrongerMods (ProblemPtr p, RelaxationPtr rel, ModVector &p_mods, ModVector &r_mods)
	Undo Modifications made during stronger branching. More...

virtual void	writeStats (std::ostream &) const
	Write statistics to ostream out. More...

Additional Inherited Members
Protected Attributes inherited from Minotaur::Handler
ConstraintVector	cons_

bool	modProb_
	If true, modify the original (or transformed) problem.

bool	modRel_
	If true, modify the relaxation of original (or transformed) problem.

Detailed Description

IntVarHandler class considers integer variables of a problem. It only checks integrality of the variables. It does not implement separate() function. Implements functions for isFeasible and branching.

Member Function Documentation

◆ getBranches()

Branches IntVarHandler::getBranches	(	BrCandPtr	cand,
		DoubleVector &	x,
		RelaxationPtr	rel,
		SolutionPoolPtr	s_pool
	)

virtual

Return branches for branching.

Get branches by branching on the given candidate. In the general scheme for branching, we store only bound changes, though we are also capable of storing other mods.

Parameters

[in]	cand	Candidate on which the brancher wants to branch.
[in]	x	The solution of the relaxation at the current node.
[in]	rel	The relaxation at the current node.
[in]	s_pool	Best feasible solutions found so far.

Returns: a vector of branch-objects.

Implements Minotaur::Handler.

◆ getBranchingCandidates()

void IntVarHandler::getBranchingCandidates	(	RelaxationPtr	rel,
		const DoubleVector &	x,
		ModVector &	mods,
		BrVarCandSet &	cands,
		BrCandVector &	gencands,
		bool &	is_inf
	)

virtual

find branching candidates.

A brancher will ask each handler by calling this function to list branching candidates.

Parameters

[in]	rel	Relaxation being solved at current node.
[in]	x	Solution of the relaxation.
[out]	mods	Any modifications that the handler found (Unused).
[out]	cands	The set of candidates to which branching candidates must be inserted. This set has candidates that want to branch on a single variable only. Other candidates must go into gencands.
[out]	gencands	The vector of general branching candidates. All candidates that do not want to branch on a variable dichotomy must be added in this vector.
[out]	is_inf	true if the handler finds that the problem is infeasible and the node can be pruned.

Implements Minotaur::Handler.

◆ getBrMod()

ModificationPtr IntVarHandler::getBrMod	(	BrCandPtr	cand,
		DoubleVector &	x,
		RelaxationPtr	rel,
		BranchDirection	dir
	)

virtual

Get the modifcation that creates a given (up or down) branch.

If one branch is pruned by the brancher (e.g. strong brancher), then we can apply the modifications of other branch to the relaxation without branching. This routine returns such a modification. This function is also called for obtaining modifications for strong branching on a candidate.

Parameters

[in]	cand	The candidate for which we want the modification.
[in]	x	The solution of relaxation at current node.
[in]	rel	The relaxation at current node.
[in]	dir	The Direction for which we want the modification, Up or Down?.

Returns: Modification that can be applied to the relaxation before re-solving it.

Implements Minotaur::Handler.

◆ getName()

std::string IntVarHandler::getName ( ) const

virtual

Return the name of the handler.

Implements Minotaur::Handler.

◆ isFeasible()

bool IntVarHandler::isFeasible	(	ConstSolutionPtr	sol,
		RelaxationPtr	rel,
		bool &	should_prune,
		double &	inf_meas
	)

virtual

Check if a solution is feasible.

Check if a given solution is feasible for the constraints that are handled by this handler. should_prune is true if the handler finds that the problem itself is infeasible and the current node can be pruned (which is different from a solution not being feasible).

Parameters

[in]	sol	The solution of the relaxation whose feasibility we want to test.
[in]	rel	The relaxation.
[out]	should_prune	True if the relaxation is infeasible and we can prune the node associated.
[out]	inf_meas	A measure of infeasibility. It may be used by heuristics and other code to make the tree-search faster. Computing this value is optional.

Returns: True if sol is feasible for constraints/objective asociated with this handler. False if sol is not feasible.

Implements Minotaur::Handler.

◆ isNeeded()

bool IntVarHandler::isNeeded ( )

virtual

Return true if this handler is needed for the problem.

It is useful to know if a handler is required or not. For example, a handler may be deleted if it is not needed.

Reimplemented from Minotaur::Handler.

◆ presolve()

SolveStatus Minotaur::IntVarHandler::presolve	(	PreModQ *	,
		bool *	,
		Solution **
	)

inlinevirtual

Presolve. Don't do anything.

Implements Minotaur::Handler.

◆ presolveNode()

bool Minotaur::IntVarHandler::presolveNode	(	RelaxationPtr	,
		NodePtr	,
		SolutionPoolPtr	,
		ModVector &	,
		ModVector &
	)

inlinevirtual

Does nothing.

Implements Minotaur::Handler.

◆ relaxInitFull()

void IntVarHandler::relaxInitFull	(	RelaxationPtr	rel,
		SolutionPool *	sp,
		bool *	is_inf
	)

virtual

Create root relaxation if doing full node relaxations.

This method is used to add all the variables and constraints handled by this handler, with the understanding that nodes will also be fully rebuilt. The relaxation is already created, it should not be freed or re-allocated.

Parameters

[in,out]	rel	The relaxation that is being constructed.
[in]	Solution	pool for storing any new solutions found.
[out]	is_inf	is true if the handler finds that the problem is infeasible.

Implements Minotaur::Handler.

◆ relaxInitInc()

void IntVarHandler::relaxInitInc	(	RelaxationPtr	rel,
		SolutionPool *	sp,
		bool *	is_inf
	)

virtual

Create root relaxation if doing incremental node relaxations.

This method is used to add all the variables and constraints handled by this handler, with the understanding that nodes will incrementally relaxed. The relaxation is already created, it should not be freed or re-allocated.

Parameters

[in,out]	rel	The relaxation that is being constructed.
[in]	Solution	pool for storing any new solutions found.
[out]	is_inf	is true if the handler finds that the problem is infeasible.

Implements Minotaur::Handler.

◆ relaxNodeFull()

void IntVarHandler::relaxNodeFull	(	NodePtr	node,
		RelaxationPtr	rel,
		bool *	is_inf
	)

virtual

Create a relaxation for a node, building from scratch.

Create a relaxation of the constraints. Either this method, or relaxNodeInc should be called at each node. Here, we only make minor modifications to the same relaxation.

Parameters

[in]	node	is the node for which relaxation is to be created.
[in]	rel	is the relaxation that is being constructed. Do not allocate or re-allocate space for it. Just add new variables or constraints to it.
[out]	is_inf	is true if the node can be pruned.

Implements Minotaur::Handler.

◆ relaxNodeInc()

void IntVarHandler::relaxNodeInc	(	NodePtr	node,
		RelaxationPtr	rel,
		bool *	is_inf
	)

virtual

Create an incremental relaxation for a node.

Create a relaxation of the constraints. Either this method, or nodeRelaxFull relax should be called at root node. Usually we only make minor modifications to the same relaxation.

Parameters

[in]	node	is the node for which relaxation is to be created.
[in]	rel	is the relaxation that is being constructed. Do not allocate or re-allocate space for it. Just add new variables or constraints to it.
[out]	is_inf	is true if the node can be pruned.

Implements Minotaur::Handler.

◆ separate()

void Minotaur::IntVarHandler::separate	(	ConstSolutionPtr	,
		NodePtr	,
		RelaxationPtr	,
		CutManager *	,
		SolutionPoolPtr	,
		ModVector &	,
		ModVector &	,
		bool *	,
		SeparationStatus *
	)

inlinevirtual

We do not need separation for this handler. So we just return without doing anything.

Implements Minotaur::Handler.

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

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

Public Member Functions

Additional Inherited Members

Detailed Description

Member Function Documentation

◆ getBranches()

◆ getBranchingCandidates()

◆ getBrMod()

◆ getName()

◆ isFeasible()

◆ isNeeded()

◆ presolve()

◆ presolveNode()

◆ relaxInitFull()

◆ relaxInitInc()

◆ relaxNodeFull()

◆ relaxNodeInc()

◆ separate()