Google OR-Tools v9.11
a fast and portable software suite for combinatorial optimization
Loading...
Searching...
No Matches
Public Member Functions | List of all members
operations_research::bop::LinearRelaxation Class Reference

#include <bop_fs.h>

Inheritance diagram for operations_research::bop::LinearRelaxation:
operations_research::bop::BopOptimizerBase

Public Member Functions

 LinearRelaxation (const BopParameters &parameters, absl::string_view name)
 
 ~LinearRelaxation () override
 
bool ShouldBeRun (const ProblemState &problem_state) const override
 
Status Optimize (const BopParameters &parameters, const ProblemState &problem_state, LearnedInfo *learned_info, TimeLimit *time_limit) override
 
- Public Member Functions inherited from operations_research::bop::BopOptimizerBase
 BopOptimizerBase (absl::string_view name)
 
virtual ~BopOptimizerBase ()
 
const std::string & name () const
 Returns the name given at construction.
 

Additional Inherited Members

- Public Types inherited from operations_research::bop::BopOptimizerBase
enum  Status {
  OPTIMAL_SOLUTION_FOUND , SOLUTION_FOUND , INFEASIBLE , LIMIT_REACHED ,
  INFORMATION_FOUND , CONTINUE , ABORT
}
 
- Static Public Member Functions inherited from operations_research::bop::BopOptimizerBase
static std::string GetStatusString (Status status)
 Returns a string describing the status.
 
- Protected Attributes inherited from operations_research::bop::BopOptimizerBase
const std::string name_
 
StatsGroup stats_
 

Detailed Description

This class computes the linear relaxation of the state problem. Optimize() fills the relaxed values (possibly floating values) that can be used by other optimizers as BopSatLpFirstSolutionGenerator for instance, and the lower bound.

Definition at line 103 of file bop_fs.h.

Constructor & Destructor Documentation

◆ LinearRelaxation()

operations_research::bop::LinearRelaxation::LinearRelaxation ( const BopParameters & parameters,
absl::string_view name )

LinearRelaxation

Definition at line 371 of file bop_fs.cc.

◆ ~LinearRelaxation()

operations_research::bop::LinearRelaxation::~LinearRelaxation ( )
overridedefault

Member Function Documentation

◆ Optimize()

BopOptimizerBase::Status operations_research::bop::LinearRelaxation::Optimize ( const BopParameters & parameters,
const ProblemState & problem_state,
LearnedInfo * learned_info,
TimeLimit * time_limit )
overridevirtual

Tries to infer more information about the problem state, i.e. reduces the gap by increasing the lower bound or finding a better solution. Returns SOLUTION_FOUND when a new solution with a better objective cost is found before a time limit. The learned information is cleared and the filled with any new information about the problem, e.g. a new lower bound.

Preconditions: ShouldBeRun() must returns true.

The lp returns the objective with the offset and scaled, so we need to unscale it and then remove the offset.

Implements operations_research::bop::BopOptimizerBase.

Definition at line 475 of file bop_fs.cc.

◆ ShouldBeRun()

bool operations_research::bop::LinearRelaxation::ShouldBeRun ( const ProblemState & problem_state) const
overridevirtual

Always let the LP solver run if there is an objective. If there isn't, only let the LP solver run if the user asked for it by setting BopParameters.max_lp_solve_for_feasibility_problems to a non-zero value (a negative value means no limit).

Todo
(user): also deal with problem_already_solved_

Implements operations_research::bop::BopOptimizerBase.

Definition at line 470 of file bop_fs.cc.

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