operations_research::SteepestSearch Class Reference

The consistency level is maintained up to kFreeAndUncovered. More...

Detailed Description

The consistency level is maintained up to kFreeAndUncovered.

Once we have a first solution to the problem, there may be (most often, there are) elements in E that are covered several times. To decrease the total cost, SteepestSearch tries to eliminate some redundant S_j's from the solution or equivalently, to flip some x_j's from 1 to 0. the algorithm gets its name because it goes in the steepest immediate direction, taking the S_j with the largest total cost.

Definition at line 371 of file set_cover_heuristics.h.

#include <set_cover_heuristics.h>

Inheritance diagram for operations_research::SteepestSearch:

Public Member Functions
	SteepestSearch (SetCoverInvariant *inv)
	SteepestSearch (SetCoverInvariant *inv, absl::string_view name)
bool	NextSolution (const SubsetBoolVector &in_focus) final
	SteepestSearch.
bool	NextSolution (absl::Span< const SubsetIndex > focus) final
bool	NextSolution () final
	Virtual methods that must be implemented by derived classes.
Public Member Functions inherited from operations_research::BoolVectorBasedSolutionGenerator
	BoolVectorBasedSolutionGenerator (SetCoverInvariant *inv, SetCoverInvariant::ConsistencyLevel consistency_level, absl::string_view class_name, absl::string_view name)
Public Member Functions inherited from operations_research::SetCoverSolutionGenerator
	SetCoverSolutionGenerator (SetCoverInvariant *inv, SetCoverInvariant::ConsistencyLevel consistency_level, absl::string_view class_name, absl::string_view name)
virtual	~SetCoverSolutionGenerator ()=default
void	SetName (const absl::string_view name)
SetCoverInvariant *	inv () const
virtual SetCoverSolutionGenerator &	ResetLimits ()
	Resets the limits to their default values.
SetCoverSolutionGenerator &	SetMaxIterations (int64_t max_iterations)
	Sets the maximum number of iterations.
int64_t	max_iterations () const
	Returns the maximum number of iterations.
SetCoverSolutionGenerator &	SetTimeLimitInSeconds (double seconds)
	Sets the time limit in seconds.
absl::Duration	run_time () const
double	run_time_in_seconds () const
	Returns the total elapsed runtime in seconds.
double	run_time_in_microseconds () const
	Returns the total elapsed runtime in microseconds.
std::string	name () const
	Returns the name of the heuristic.
std::string	class_name () const
	Returns the name of the class.
Cost	cost () const
	Returns the current cost of the solution in the invariant.
bool	CheckInvariantConsistency () const

Additional Inherited Members
Protected Member Functions inherited from operations_research::SetCoverSolutionGenerator
SetCoverModel *	model () const
	Accessors.
BaseInt	num_subsets () const
double	time_limit_in_seconds () const
	The time limit in seconds.
Protected Attributes inherited from operations_research::SetCoverSolutionGenerator
absl::Duration	run_time_
	run_time_ is an abstract duration for the time spent in NextSolution().
SetCoverInvariant::ConsistencyLevel	consistency_level_
	The consistency needed by the solution generator.

Constructor & Destructor Documentation

SteepestSearch() [1/2]

operations_research::SteepestSearch::SteepestSearch ( SetCoverInvariant * inv )

inlineexplicit

Definition at line 373 of file set_cover_heuristics.h.

SteepestSearch() [2/2]

operations_research::SteepestSearch::SteepestSearch ( SetCoverInvariant * inv, absl::string_view name )

inline

Definition at line 376 of file set_cover_heuristics.h.

Member Function Documentation

NextSolution() [1/3]

bool operations_research::BoolVectorBasedSolutionGenerator::NextSolution ( )

inlinefinalvirtual

Virtual methods that must be implemented by derived classes.

Computes the next full solution taking into account all the subsets.

Reimplemented from operations_research::BoolVectorBasedSolutionGenerator.

Definition at line 222 of file set_cover_heuristics.h.

NextSolution() [2/3]

bool operations_research::BoolVectorBasedSolutionGenerator::NextSolution ( absl::Span< const SubsetIndex > focus )

inlinefinalvirtual

Computes the next partial solution considering only the subsets whose indices are in focus.

Reimplemented from operations_research::BoolVectorBasedSolutionGenerator.

Definition at line 218 of file set_cover_heuristics.h.

NextSolution() [3/3]

bool operations_research::SteepestSearch::NextSolution ( const SubsetBoolVector & in_focus )

finalvirtual

SteepestSearch.

Return false if inv() contains no solution.

Todo

(user): This should be relaxed for partial solutions.

Create priority queue with cost of using a subset, by decreasing order. Do it only for selected AND removable subsets.

Todo

(user): change this to enable working on partial solutions.

Reimplemented from operations_research::BoolVectorBasedSolutionGenerator.

Definition at line 475 of file set_cover_heuristics.cc.

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

• ortools/set_cover/set_cover_heuristics.h
• ortools/set_cover/set_cover_heuristics.cc