Detect and process implied free variables. More...
#include <CoinPresolveImpliedFree.hpp>
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 () | |
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CoinPresolveAction (const CoinPresolveAction *next) | |
Construct a postsolve object and add it to the transformation list. | |
void | setNext (const CoinPresolveAction *nextAction) |
modify next (when building rather than passing) | |
virtual | ~CoinPresolveAction () |
Virtual destructor. |
Static Public Member Functions | |
static const CoinPresolveAction * | presolve (CoinPresolveMatrix *prob, const CoinPresolveAction *next, int &fillLevel) |
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static void | throwCoinError (const char *error, const char *ps_routine) |
Stub routine to throw exceptions. |
Private Member Functions | |
implied_free_action (int nactions, const action *actions, const CoinPresolveAction *next) |
Private Attributes | |
const int | nactions_ |
const action *const | actions_ |
Additional Inherited Members | |
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const CoinPresolveAction * | next |
The next presolve transformation. |
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 28 of file CoinPresolveImpliedFree.hpp.
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inlineprivate |
Definition at line 41 of file CoinPresolveImpliedFree.hpp.
implied_free_action::~implied_free_action | ( | ) |
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virtual |
A name for debug printing.
It is expected that the name is not stored in the transform itself.
Implements CoinPresolveAction.
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static |
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virtual |
Apply the postsolve transformation for this particular presolve action.
Implements CoinPresolveAction.
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private |
Definition at line 38 of file CoinPresolveImpliedFree.hpp.
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private |
Definition at line 39 of file CoinPresolveImpliedFree.hpp.