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CglKnapsackCover Class Reference

Knapsack Cover Cut Generator Class. More...

#include <CglKnapsackCover.hpp>

Inheritance diagram for CglKnapsackCover:

CglCutGenerator 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 CglCutGeneratorclone () const
 Clone.
CglKnapsackCoveroperator= (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.

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 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:
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