implied_free_action Class Reference

Detect and process implied free variables. More...

#include <CoinPresolveImpliedFree.hpp>

Inheritance diagram for implied_free_action:

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Collaboration diagram for implied_free_action:

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List of all members.

Classes
struct	action
Public Member Functions
const char *	name () const
	A name for debug printing.
void	postsolve (CoinPostsolveMatrix *prob) const
	Apply the postsolve transformation for this particular presolve action.
	~implied_free_action ()
Static Public Member Functions
static const CoinPresolveAction *	presolve (CoinPresolveMatrix prob, const CoinPresolveAction next, int &fillLevel)
Private Member Functions
	implied_free_action (int nactions, const action actions, const CoinPresolveAction next)
Private Attributes
const int	nactions_
const action *const	actions_

Detailed Description

Detect and process implied free variables.

Consider a singleton variable x (i.e., a variable involved in only one constraint). Suppose that the bounds on that constraint, combined with the bounds on the other variables involved in the constraint, are such that even the worst case values of the other variables still imply bounds for x which are tighter than the variable's original bounds. Since x can never reach its upper or lower bounds, it is an implied free variable. Both x and the constraint can be deleted from the problem.

The transform also handles more complicated variations, where x is not a singleton.

Definition at line 27 of file CoinPresolveImpliedFree.hpp.

Constructor & Destructor Documentation

implied_free_action::implied_free_action	(	int	nactions,
		const action *	actions,
		const CoinPresolveAction *	next
	)			`[inline, private]`

Definition at line 40 of file CoinPresolveImpliedFree.hpp.

implied_free_action::~implied_free_action ( )

Member Function Documentation

const char* implied_free_action::name ( ) const [virtual]

A name for debug printing.

It is expected that the name is not stored in the transform itself.

Implements CoinPresolveAction.

static const CoinPresolveAction* implied_free_action::presolve	(	CoinPresolveMatrix *	prob,
		const CoinPresolveAction *	next,
		int &	fillLevel
	)			`[static]`