#include <CxUnivarHandler.h>

Inheritance diagram for Minotaur::CxUnivarHandler:

Collaboration diagram for Minotaur::CxUnivarHandler:

[legend]

Public Member Functions
	CxUnivarHandler (EnvPtr env, ProblemPtr problem)
	Default constructor.

	~CxUnivarHandler ()
	Destroy.

void	addConstraint (ConstraintPtr newcon, ConstVariablePtr ivar, ConstVariablePtr ovar, char sense='E')

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

void	relaxInitFull (RelaxationPtr, SolutionPool , bool )

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

bool	isFeasible (ConstSolutionPtr sol, RelaxationPtr relaxation, bool &should_prune, double &inf_meas)

void	separate (ConstSolutionPtr sol, NodePtr node, RelaxationPtr rel, CutManager cutman, SolutionPoolPtr s_pool, ModVector &p_mods, ModVector &r_mods, bool sol_found, SeparationStatus *status)

virtual void	relaxNodeFull (NodePtr, RelaxationPtr, bool *)

virtual void	relaxNodeInc (NodePtr node, RelaxationPtr rel, bool *isInfeasible)

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

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

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

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

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

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

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...

Protected Attributes
double	eTol_
	Tolerance for constraint violation.

double	vTol_
	Tolerance for when upper and lower bounds considered equal.

ProblemPtr	problem_
	Original problem.

LoggerPtr	logger_
	Logger.

CxUnivarConstraintDataVector	cons_data_
	Internal data associated with each constraint.

DoubleVector	tmpX_
	A temporary vector of zeros, for evaluating functions.

DoubleVector	grad_
	A temporary vector of zeros, for getting gradients.

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.

Static Protected Attributes
static const std::string	me_ = "CxUnivarHandler: "
	For printing.

Detailed Description

An CxUnivarHandler handles convex univariate functions. The upper relaxation is handled with the single secant inequality, the lower relaxation is handled with linearizations. TODO: This class could easily be extended to handle perspective cuts if a binary varaible is known which turns off the input variable

Member Function Documentation

◆ addConstraint() [1/2]

void CxUnivarHandler::addConstraint	(	ConstraintPtr	newcon,
		ConstVariablePtr	ivar,
		ConstVariablePtr	ovar,
		char	sense = `'E'`
	)

Adds constraint to list (as all handlers), but also constructs the associated constraint data.

◆ addConstraint() [2/2]

void Minotaur::CxUnivarHandler::addConstraint ( ConstraintPtr newcon )

inlinevirtual

Add constraint to be handled by this handler.

Parameters

[in] newcon Constraint to be added.

Reimplemented from Minotaur::Handler.

◆ getBranches()

Branches CxUnivarHandler::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 CxUnivarHandler::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 CxUnivarHandler::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 CxUnivarHandler::getName ( ) const

virtual

Return the name of the handler.

Implements Minotaur::Handler.

◆ isFeasible()

bool CxUnivarHandler::isFeasible	(	ConstSolutionPtr	sol,
		RelaxationPtr	relaxation,
		bool &	should_prune,
		double &	inf_meas
	)

virtual

Check feasibility.

Implements Minotaur::Handler.

◆ presolve()

SolveStatus CxUnivarHandler::presolve	(	PreModQ *	pre_mods,
		bool *	changed,
		Solution **	sol
	)

virtual

Initial presolve.

Do the initial presolve. For now we will assume that presolve modifies the given problem. We do not create a new problem. All modifications that require post-processing for getting the solution back are prepended to 'pre_mods' by the handler.

Parameters

[in]	pre_mods	A pointer to a queue of PreMod objects. Modifications made by the presolver must be prepended (not appended) to pre_mods. The order is important for post-solve.
[out]	changed	True if the presolve modified the problem.

Returns: status of presolve.

Parameters

[out] sol Optimal solution found by the handler, if any. The status must be SolvedOptimal if and only if sol is created.

Implements Minotaur::Handler.

◆ presolveNode()

bool CxUnivarHandler::presolveNode	(	RelaxationPtr	rel,
		NodePtr	node,
		SolutionPoolPtr	s_pool,
		ModVector &	p_mods,
		ModVector &	r_mods
	)

virtual

Presolve the problem and its relaxation at a node.

Presolve the problem and its relaxation at a given node. Bound propagation and other simple modifications can be made in this function. It is called after the node relaxation is setup but before it is solved. Both the problem and its relaxation are presolved. Changes to the problem are stored in the tree. Changes to the relaxation are optional and may or may not be stored in the tree.

Parameters

[in]	rel	Relaxation at the current node.
[in]	node	Current node.
[in]	s_pool	Pool of solutions.
[in]	p_mods	Unused. Modifications to the problem that must be stored in this node so that they are applied to all descendant nodes as well. All modifications must be appended not prepended.
[out]	r_mods	Modifications to the relaxation that must be stored in this node so that they are applied to all descendant nodes as well. All modifications must be appended not prepended. This may be unnecessary in certain algorithms.

Returns: true if Node can be pruned because infeasibility is detected.

Implements Minotaur::Handler.

◆ relaxInitFull()

void Minotaur::CxUnivarHandler::relaxInitFull	(	RelaxationPtr	,
		SolutionPool *	,
		bool *
	)

inlinevirtual

For this handler, nothing is different at root or any node when doing full relax

Implements Minotaur::Handler.

◆ relaxInitInc()

void CxUnivarHandler::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()

virtual void Minotaur::CxUnivarHandler::relaxNodeFull	(	NodePtr	,
		RelaxationPtr	,
		bool *
	)

inlinevirtual

Create a relaxation by adding the secant inequality for the upper estimator, and some number of linearization inequalities, at a minimum from the end points

Implements Minotaur::Handler.

◆ relaxNodeInc()

void CxUnivarHandler::relaxNodeInc	(	NodePtr	node,
		RelaxationPtr	rel,
		bool *	isInfeasible
	)

virtual

Create a relaxation by updating the secant inequality for the upper estimator, and adding lineariations at the end points, if they are new

Implements Minotaur::Handler.

◆ separate()

void CxUnivarHandler::separate	(	ConstSolutionPtr	sol,
		NodePtr	node,
		RelaxationPtr	rel,
		CutManager *	cutman,
		SolutionPoolPtr	s_pool,
		ModVector &	p_mods,
		ModVector &	r_mods,
		bool *	sol_found,
		SeparationStatus *	status
	)

virtual

Not implemented yet. Eventually, could add violated linearization inequalities for underestimator portion

Implements Minotaur::Handler.

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

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

Public Member Functions

Protected Attributes

Static Protected Attributes

Detailed Description

Member Function Documentation

◆ addConstraint() [1/2]

◆ addConstraint() [2/2]

◆ getBranches()

◆ getBranchingCandidates()

◆ getBrMod()

◆ getName()

◆ isFeasible()

◆ presolve()

◆ presolveNode()

◆ relaxInitFull()

◆ relaxInitInc()

◆ relaxNodeFull()

◆ relaxNodeInc()

◆ separate()