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# CglKnapsackCover Class Reference

Knapsack Cover Cut Generator Class. More...

`#include <CglKnapsackCover.hpp>`

Inheritance diagram for CglKnapsackCover:

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Collaboration diagram for CglKnapsackCover:

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List of all members.

## Public Member Functions
void | setTestedRowIndices (int num, const int *ind)
| A method to set which rows should be tested for knapsack covers.
Generate Cuts
virtual void | generateCuts (const OsiSolverInterface &si, OsiCuts &cs, const CglTreeInfo info=CglTreeInfo()) const
| Generate knapsack cover cuts for the model of the solver interface, si.
Constructors and destructors
| CglKnapsackCover ()
| Default constructor.
| CglKnapsackCover (const CglKnapsackCover &)
| Copy constructor.
virtual CglCutGenerator * | clone () const
| Clone.
CglKnapsackCover & | operator= (const CglKnapsackCover &rhs)
| Assignment operator.
virtual | ~CglKnapsackCover ()
| Destructor.
virtual std::string | generateCpp (FILE *fp)
| Create C++ lines to get to current state.
Sets and gets
void | setMaxInKnapsack (int value)
| Set limit on number in knapsack.
int | getMaxInKnapsack () const
| get limit on number in knapsack
void | switchOffExpensive ()
| Switch off expensive cuts.
void | switchOnExpensive ()
| Switch on expensive cuts.
## Private Member Functions
Private methods
int | deriveAKnapsack (const OsiSolverInterface &si, OsiCuts &cs, CoinPackedVector &krow, bool treatAsLRow, double &b, int *complement, double *xstar, int rowIndex, int numberElements, const int *index, const double *element) const
| deriveAKnapsack returns 1 if it is able to derive a (canonical) knapsack inequality in binary variables of the form ax<=b from the rowIndex-th row in the model, returns 0 otherwise.
int | deriveAKnapsack (const OsiSolverInterface &si, OsiCuts &cs, CoinPackedVector &krow, double &b, int *complement, double *xstar, int rowIndex, const CoinPackedVectorBase &matrixRow) const
| deriveAKnapsack returns 1 if it is able to derive a (canonical) knapsack inequality in binary variables of the form ax<=b from the rowIndex-th row in the model, returns 0 otherwise.
int | findExactMostViolatedMinCover (int nCols, int row, CoinPackedVector &krow, double b, double *xstar, CoinPackedVector &cover, CoinPackedVector &remainder) const
| Find a violated minimal cover from a canonical form knapsack inequality by solving the -most- violated cover problem and postprocess to ensure minimality.
int | findLPMostViolatedMinCover (int nCols, int row, CoinPackedVector &krow, double &b, double *xstar, CoinPackedVector &cover, CoinPackedVector &remainder) const
| Find the most violate minimum cover by solving the lp-relaxation of the most-violate-min-cover problem.
int | findGreedyCover (int row, CoinPackedVector &krow, double &b, double *xstar, CoinPackedVector &cover, CoinPackedVector &remainder) const
| find a minimum cover by a simple greedy approach
int | liftCoverCut (double &b, int nRowElem, CoinPackedVector &cover, CoinPackedVector &remainder, CoinPackedVector &cut) const
| lift the cover inequality
int | liftAndUncomplementAndAdd (double rowub, CoinPackedVector &krow, double &b, int *complement, int row, CoinPackedVector &cover, CoinPackedVector &remainder, OsiCuts &cs) const
| sequence-independent lift and uncomplement and add the resulting cut to the cut set
void | seqLiftAndUncomplementAndAdd (int nCols, double *xstar, int *complement, int row, int nRowElem, double &b, CoinPackedVector &cover, CoinPackedVector &remainder, OsiCuts &cs) const
| sequence-dependent lift, uncomplement and add the resulting cut to the cut set
void | liftUpDownAndUncomplementAndAdd (int nCols, double *xstar, int *complement, int row, int nRowElem, double &b, CoinPackedVector &fracCover, CoinPackedVector &atOne, CoinPackedVector &remainder, OsiCuts &cs) const
| sequence-dependent lift binary variables either up or down, uncomplement and add to the cut set
int | findPseudoJohnAndEllisCover (int row, CoinPackedVector &krow, double &b, double *xstar, CoinPackedVector &cover, CoinPackedVector &remainder) const
| find a cover using a variation of the logic found in OSL (w/o SOS)
int | findJohnAndEllisCover (int row, CoinPackedVector &krow, double &b, double *xstar, CoinPackedVector &fracCover, CoinPackedVector &atOnes, CoinPackedVector &remainder) const
| find a cover using the basic logic found in OSL (w/o SOS)
int | exactSolveKnapsack (int n, double c, double const *pp, double const *ww, double &z, int *x) const
| A C-style implementation of the Horowitz-Sahni exact solution procedure for solving knapsack problem.
## Private Attributes
Private member data
double | epsilon_
| epsilon
double | epsilon2_
| Tolerance to use for violation - bigger than epsilon_.
double | onetol_
| 1-epsilon
int | maxInKnapsack_
| Maximum in knapsack.
int | numRowsToCheck_
| which rows to look at.
int * | rowsToCheck_
| epsilon
bool | expensiveCuts_
| exactKnapsack can be expensive - this switches off some
## Friends
void | CglKnapsackCoverUnitTest (const OsiSolverInterface *siP, const std::string mpdDir)
| A function that tests the methods in the CglKnapsackCover class.

## Detailed Description

Knapsack Cover Cut Generator Class.

Definition at line 11 of file CglKnapsackCover.hpp.

## Constructor & Destructor Documentation

CglKnapsackCover::CglKnapsackCover | ( |  | ) |

Default constructor.

CglKnapsackCover::CglKnapsackCover | ( | const CglKnapsackCover & |  | ) |

Copy constructor.

virtual CglKnapsackCover::~CglKnapsackCover | ( |  | ) | `[virtual]`

Destructor.

## Member Function Documentation

void CglKnapsackCover::setTestedRowIndices | ( | int | num,
|  | const int * | ind |
| ) |  |  |

A method to set which rows should be tested for knapsack covers.

virtual void CglKnapsackCover::generateCuts | ( | const OsiSolverInterface & | si,
|  | OsiCuts & | cs,
|  | const CglTreeInfo | info = `CglTreeInfo()` |
| ) |  |  | const`[virtual]`

Generate knapsack cover cuts for the model of the solver interface, si.

Insert the generated cuts into OsiCut, cs.

Implements CglCutGenerator.

virtual CglCutGenerator* CglKnapsackCover::clone | ( |  | ) | const`[virtual]`

Clone.

Implements CglCutGenerator.

CglKnapsackCover& CglKnapsackCover::operator= | ( | const CglKnapsackCover & | rhs | ) |

Assignment operator.

virtual std::string CglKnapsackCover::generateCpp | ( | FILE * | fp | ) | `[virtual]`

Create C++ lines to get to current state.

Reimplemented from CglCutGenerator.

void CglKnapsackCover::setMaxInKnapsack | ( | int | value | ) | `[inline]`

Set limit on number in knapsack.

Definition at line 56 of file CglKnapsackCover.hpp.

References maxInKnapsack_.

int CglKnapsackCover::getMaxInKnapsack | ( |  | ) | const`[inline]`

get limit on number in knapsack

Definition at line 59 of file CglKnapsackCover.hpp.

References maxInKnapsack_.

void CglKnapsackCover::switchOffExpensive | ( |  | ) | `[inline]`

Switch off expensive cuts.

Definition at line 62 of file CglKnapsackCover.hpp.

References expensiveCuts_.

void CglKnapsackCover::switchOnExpensive | ( |  | ) | `[inline]`

Switch on expensive cuts.

Definition at line 65 of file CglKnapsackCover.hpp.

References expensiveCuts_.

int CglKnapsackCover::deriveAKnapsack | ( | const OsiSolverInterface & | si,
|  | OsiCuts & | cs,
|  | CoinPackedVector & | krow,
|  | bool | treatAsLRow,
|  | double & | b,
|  | int * | complement,
|  | double * | xstar,
|  | int | rowIndex,
|  | int | numberElements,
|  | const int * | index,
|  | const double * | element |
| ) |  |  | const`[private]`

deriveAKnapsack returns 1 if it is able to derive a (canonical) knapsack inequality in binary variables of the form ax<=b from the rowIndex-th row in the model, returns 0 otherwise.

int CglKnapsackCover::deriveAKnapsack | ( | const OsiSolverInterface & | si,
|  | OsiCuts & | cs,
|  | CoinPackedVector & | krow,
|  | double & | b,
|  | int * | complement,
|  | double * | xstar,
|  | int | rowIndex,
|  | const CoinPackedVectorBase & | matrixRow |
| ) |  |  | const`[private]`

deriveAKnapsack returns 1 if it is able to derive a (canonical) knapsack inequality in binary variables of the form ax<=b from the rowIndex-th row in the model, returns 0 otherwise.

int CglKnapsackCover::findExactMostViolatedMinCover | ( | int | nCols,
|  | int | row,
|  | CoinPackedVector & | krow,
|  | double | b,
|  | double * | xstar,
|  | CoinPackedVector & | cover,
|  | CoinPackedVector & | remainder |
| ) |  |  | const`[private]`

Find a violated minimal cover from a canonical form knapsack inequality by solving the -most- violated cover problem and postprocess to ensure minimality.

int CglKnapsackCover::findLPMostViolatedMinCover | ( | int | nCols,
|  | int | row,
|  | CoinPackedVector & | krow,
|  | double & | b,
|  | double * | xstar,
|  | CoinPackedVector & | cover,
|  | CoinPackedVector & | remainder |
| ) |  |  | const`[private]`

Find the most violate minimum cover by solving the lp-relaxation of the most-violate-min-cover problem.

int CglKnapsackCover::findGreedyCover | ( | int | row,
|  | CoinPackedVector & | krow,
|  | double & | b,
|  | double * | xstar,
|  | CoinPackedVector & | cover,
|  | CoinPackedVector & | remainder |
| ) |  |  | const`[private]`

find a minimum cover by a simple greedy approach

int CglKnapsackCover::liftCoverCut | ( | double & | b,
|  | int | nRowElem,
|  | CoinPackedVector & | cover,
|  | CoinPackedVector & | remainder,
|  | CoinPackedVector & | cut |
| ) |  |  | const`[private]`

lift the cover inequality

int CglKnapsackCover::liftAndUncomplementAndAdd | ( | double | rowub,
|  | CoinPackedVector & | krow,
|  | double & | b,
|  | int * | complement,
|  | int | row,
|  | CoinPackedVector & | cover,
|  | CoinPackedVector & | remainder,
|  | OsiCuts & | cs |
| ) |  |  | const`[private]`

sequence-independent lift and uncomplement and add the resulting cut to the cut set

void CglKnapsackCover::seqLiftAndUncomplementAndAdd | ( | int | nCols,
|  | double * | xstar,
|  | int * | complement,
|  | int | row,
|  | int | nRowElem,
|  | double & | b,
|  | CoinPackedVector & | cover,
|  | CoinPackedVector & | remainder,
|  | OsiCuts & | cs |
| ) |  |  | const`[private]`

sequence-dependent lift, uncomplement and add the resulting cut to the cut set

void CglKnapsackCover::liftUpDownAndUncomplementAndAdd | ( | int | nCols,
|  | double * | xstar,
|  | int * | complement,
|  | int | row,
|  | int | nRowElem,
|  | double & | b,
|  | CoinPackedVector & | fracCover,
|  | CoinPackedVector & | atOne,
|  | CoinPackedVector & | remainder,
|  | OsiCuts & | cs |
| ) |  |  | const`[private]`

sequence-dependent lift binary variables either up or down, uncomplement and add to the cut set

int CglKnapsackCover::findPseudoJohnAndEllisCover | ( | int | row,
|  | CoinPackedVector & | krow,
|  | double & | b,
|  | double * | xstar,
|  | CoinPackedVector & | cover,
|  | CoinPackedVector & | remainder |
| ) |  |  | const`[private]`

find a cover using a variation of the logic found in OSL (w/o SOS)

int CglKnapsackCover::findJohnAndEllisCover | ( | int | row,
|  | CoinPackedVector & | krow,
|  | double & | b,
|  | double * | xstar,
|  | CoinPackedVector & | fracCover,
|  | CoinPackedVector & | atOnes,
|  | CoinPackedVector & | remainder |
| ) |  |  | const`[private]`

find a cover using the basic logic found in OSL (w/o SOS)

int CglKnapsackCover::exactSolveKnapsack | ( | int | n,
|  | double | c,
|  | double const * | pp,
|  | double const * | ww,
|  | double & | z,
|  | int * | x |
| ) |  |  | const`[private]`

A C-style implementation of the Horowitz-Sahni exact solution procedure for solving knapsack problem.

(ToDo: implement the more efficient dynamic programming approach)

(Reference: Martello and Toth, Knapsack Problems, Wiley, 1990, p30.)

## Friends And Related Function Documentation

void CglKnapsackCoverUnitTest | ( | const OsiSolverInterface * | siP,
|  | const std::string | mpdDir |
| ) |  |  | `[friend]`

A function that tests the methods in the CglKnapsackCover class.

The only reason for it not to be a member method is that this way it doesn't have to be compiled into the library. And that's a gain, because the library should be compiled with optimization on, but this method should be compiled with debugging.

## Member Data Documentation

double CglKnapsackCover::epsilon_`[private]`

epsilon

Definition at line 231 of file CglKnapsackCover.hpp.

double CglKnapsackCover::epsilon2_`[private]`

Tolerance to use for violation - bigger than epsilon_.

Definition at line 233 of file CglKnapsackCover.hpp.

double CglKnapsackCover::onetol_`[private]`

1-epsilon

Definition at line 235 of file CglKnapsackCover.hpp.

int CglKnapsackCover::maxInKnapsack_`[private]`

Maximum in knapsack.

Definition at line 237 of file CglKnapsackCover.hpp.

Referenced by getMaxInKnapsack(), and setMaxInKnapsack().

int CglKnapsackCover::numRowsToCheck_`[private]`

which rows to look at.

If specified, only these rows will be considered for generating knapsack covers. Otherwise all rows will be tried

Definition at line 240 of file CglKnapsackCover.hpp.

int* CglKnapsackCover::rowsToCheck_`[private]`

epsilon

Definition at line 241 of file CglKnapsackCover.hpp.

bool CglKnapsackCover::expensiveCuts_`[private]`

exactKnapsack can be expensive - this switches off some

Definition at line 243 of file CglKnapsackCover.hpp.

Referenced by switchOffExpensive(), and switchOnExpensive().

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

- /home/coin/SVN-release/Cgl-0.53.1/Cgl/src/CglKnapsackCover/CglKnapsackCover.hpp