An efficient unconstrained elimination sequence algorithm. More...

#include <defaultEliminationSequenceStrategy.h>

Inheritance diagram for gum::DefaultEliminationSequenceStrategy:

Collaboration diagram for gum::DefaultEliminationSequenceStrategy:

Public Member Functions
Constructors / Destructors
	DefaultEliminationSequenceStrategy (double theRatio=GUM_QUASI_RATIO, double theThreshold=GUM_WEIGHT_THRESHOLD)
	default constructor (uses an empty graph) More...

	DefaultEliminationSequenceStrategy (UndiGraph graph, const NodeProperty< Size > dom_sizes, double ratio=GUM_QUASI_RATIO, double threshold=GUM_WEIGHT_THRESHOLD)
	constructor for an a priori non empty graph More...

	DefaultEliminationSequenceStrategy (const DefaultEliminationSequenceStrategy &from)
	copy constructor More...

	DefaultEliminationSequenceStrategy (DefaultEliminationSequenceStrategy &&)
	move constructor More...

virtual	~DefaultEliminationSequenceStrategy ()
	destructor More...

virtual DefaultEliminationSequenceStrategy *	newFactory () const final
	creates a new elimination sequence of the same type as the current object, but this sequence contains only an empty graph More...

virtual DefaultEliminationSequenceStrategy *	copyFactory () const final
	virtual copy constructor More...

Accessors / Modifiers
virtual bool	setGraph (UndiGraph graph, const NodeProperty< Size > dom_sizes) final
	sets a new graph to be triangulated More...

virtual void	clear () final
	clears the sequence (to prepare, for instance, a new elimination sequence) More...

virtual NodeId	nextNodeToEliminate () final
	returns the new node to be eliminated within the triangulation algorithm More...

virtual void	askFillIns (bool do_it) final
	if the elimination sequence is able to compute fill-ins, we indicate whether we want this feature to be activated More...

virtual bool	providesFillIns () const final
	indicates whether the fill-ins generated by the eliminated nodes, if needed, will be computed by the elimination sequence, or need be computed by the triangulation itself. More...

virtual bool	providesGraphUpdate () const final
	indicates whether the elimination sequence updates by itself the graph after a node has been eliminated More...

virtual void	eliminationUpdate (const NodeId node) final
	performs all the graph/fill-ins updates provided (if any) More...

virtual const EdgeSet &	fillIns () final
	in case fill-ins are provided, this function returns the fill-ins due to all the nodes eliminated so far More...

Accessors / Modifiers
UndiGraph *	graph () const noexcept
	returns the current graph More...

const NodeProperty< Size > *	domainSizes () const noexcept
	returns the current domain sizes More...

Protected Attributes
UndiGraph *	_graph {nullptr}
	the graph to be triangulated More...

const NodeProperty< Size > *	_domain_sizes {nullptr}
	the domain sizes of the variables/nodes More...

NodeProperty< double >	_log_domain_sizes
	the log of the domain sizes of the variables/nodes More...

Detailed Description

An efficient unconstrained elimination sequence algorithm.

Class DefaultEliminationSequenceStrategy implements an unconstrained elimination sequence algorithm (that is, there is no external constraint on the possible elimination ordering). The ordering is determined as follows:

the nodes that are simplicial (i.e., those that already form a clique

with their neighbors) are eliminated first

then the nodes that are almost simplicial (i.e., if we remove one of

their neighbors, they become simplicial) and that create small cliques,

are eliminated

the quasi simplicial nodes (i.e., the nodes that do not require many

fill-ins to create cliques) that would create small cliques, are eliminated

finally, the heuristic proposed by Kjaerulff(90) is used to compute the

last nodes to be eliminated.

Definition at line 76 of file defaultEliminationSequenceStrategy.h.

Constructor & Destructor Documentation

◆ DefaultEliminationSequenceStrategy() [1/4]

gum::DefaultEliminationSequenceStrategy::DefaultEliminationSequenceStrategy	(	double	theRatio = `GUM_QUASI_RATIO`,
		double	theThreshold = `GUM_WEIGHT_THRESHOLD`
	)

default constructor (uses an empty graph)

Parameters

theRatio	the ratio used by the SimplicialSet included in the DefaultEliminationSequenceStrategy
theThreshold	the weight threshhold of the SimplicialSet included in the DefaultEliminationSequenceStrategy

Definition at line 36 of file defaultEliminationSequenceStrategy.cpp.

Referenced by copyFactory(), and newFactory().

                                            :
       __simplicial_ratio(theRatio),
       __simplicial_threshold(theThreshold) {
     // for debugging purposes
     GUM_CONSTRUCTOR(DefaultEliminationSequenceStrategy);
   }

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◆ DefaultEliminationSequenceStrategy() [2/4]

gum::DefaultEliminationSequenceStrategy::DefaultEliminationSequenceStrategy	(	UndiGraph *	graph,
		const NodeProperty< Size > *	dom_sizes,
		double	ratio = `GUM_QUASI_RATIO`,
		double	threshold = `GUM_WEIGHT_THRESHOLD`
	)

constructor for an a priori non empty graph

Parameters

graph	the graph to be triangulated, i.e., the nodes of which will be eliminated
dom_sizes	the domain sizes of the nodes to be eliminated
ratio	the ratio used by the SimplicialSet included in the DefaultEliminationSequenceStrategy
threshold	the weight threshhold of the SimplicialSet included in the DefaultEliminationSequenceStrategy

Warning: Note that we allow dom_sizes to be defined over nodes/variables that do not belong to graph. These sizes will simply be ignored. However, it is compulsory that all the nodes of graph belong to dom_sizes; the graph is altered during the triangulation.; note that, by aGrUM's rule, the graph and the domain sizes are not copied but only referenced by the elimination sequence algorithm.

Definition at line 45 of file defaultEliminationSequenceStrategy.cpp.

References setGraph().

                                             :
       __simplicial_ratio(ratio),
       __simplicial_threshold(threshold) {
     setGraph(graph, domain_sizes);
 
     // for debugging purposes
     GUM_CONSTRUCTOR(DefaultEliminationSequenceStrategy);
   }

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◆ DefaultEliminationSequenceStrategy() [3/4]

gum::DefaultEliminationSequenceStrategy::DefaultEliminationSequenceStrategy ( const DefaultEliminationSequenceStrategy & from )

copy constructor

Warning: The newly created elimination sequence strategy points toward the same undirected graph as the one contained in from but each strategy possesses its own simplicial set. As a result, if both elimination strategies are used at the same time, they will probably result in a mess because their simplicial sets won't be synchronized correctly with the changing undirected graph. So, whenever using this copy constructor, be sure that either from or the newly created strategy is used for a triangulation but not both. This will necessarily be OK in DefaultTriangulations.

Definition at line 59 of file defaultEliminationSequenceStrategy.cpp.

                                                      :
       UnconstrainedEliminationSequenceStrategy(from),
       // no need to set __log_weights because the copy of the simplicial set
       // will set it properly
       __simplicial_set(new SimplicialSet(*from.__simplicial_set,
                                          _graph,
                                          &_log_domain_sizes,
                                          &__log_weights,
                                          false)),
       __simplicial_ratio(from.__simplicial_ratio),
       __simplicial_threshold(from.__simplicial_threshold),
       __provide_fill_ins(from.__provide_fill_ins) {
     // for debugging purposes
     GUM_CONS_CPY(DefaultEliminationSequenceStrategy);
   }

◆ DefaultEliminationSequenceStrategy() [4/4]

gum::DefaultEliminationSequenceStrategy::DefaultEliminationSequenceStrategy ( DefaultEliminationSequenceStrategy && from )

move constructor

Definition at line 77 of file defaultEliminationSequenceStrategy.cpp.

References __log_weights, __simplicial_set, and gum::SimplicialSet::replaceLogWeights().

                                                 :
       UnconstrainedEliminationSequenceStrategy(std::move(from)),
       __log_weights(std::move(from.__log_weights)),
       __simplicial_set(from.__simplicial_set),
       __simplicial_ratio(from.__simplicial_ratio),
       __simplicial_threshold(from.__simplicial_threshold),
       __provide_fill_ins(from.__provide_fill_ins) {
     __simplicial_set->replaceLogWeights(&from.__log_weights, &__log_weights);
     from.__simplicial_set = nullptr;
 
     // for debugging purposes
     GUM_CONS_MOV(DefaultEliminationSequenceStrategy);
   }

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◆ ~DefaultEliminationSequenceStrategy()

gum::DefaultEliminationSequenceStrategy::~DefaultEliminationSequenceStrategy ( )

virtual

destructor

Definition at line 93 of file defaultEliminationSequenceStrategy.cpp.

References __simplicial_set.

                                                                           {
     // for debugging purposes
     GUM_DESTRUCTOR(DefaultEliminationSequenceStrategy);
 
     if (__simplicial_set != nullptr) delete __simplicial_set;
   }

Member Function Documentation

◆ __createSimplicialSet()

void gum::DefaultEliminationSequenceStrategy::__createSimplicialSet ( )

private

create a new simplicial set suited for the current graph

Definition at line 115 of file defaultEliminationSequenceStrategy.cpp.

References __log_weights, __provide_fill_ins, __simplicial_ratio, __simplicial_set, __simplicial_threshold, gum::EliminationSequenceStrategy::_graph, gum::EliminationSequenceStrategy::_log_domain_sizes, and gum::SimplicialSet::setFillIns().

Referenced by setGraph().

                                                                  {
     // remove the old simplicial set, if any
     if (__simplicial_set != nullptr) {
       delete __simplicial_set;
       __simplicial_set = nullptr;
     }
 
     if (_graph != nullptr) {
       // create a simplicial set suited for the graph
       __simplicial_set = new SimplicialSet(_graph,
                                            &_log_domain_sizes,
                                            &__log_weights,
                                            __simplicial_ratio,
                                            __simplicial_threshold);
 
       __simplicial_set->setFillIns(__provide_fill_ins);
     }
   }

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◆ askFillIns()

void gum::DefaultEliminationSequenceStrategy::askFillIns ( bool do_it )

finalvirtual

if the elimination sequence is able to compute fill-ins, we indicate whether we want this feature to be activated

Parameters

do_it when true and the elimination sequence has the ability to compute fill-ins, the elimination sequence will actually compute them (for the triangulation to use them), else they will not be available.

Implements gum::EliminationSequenceStrategy.

Definition at line 194 of file defaultEliminationSequenceStrategy.cpp.

References __provide_fill_ins, __simplicial_set, and gum::SimplicialSet::setFillIns().

                                                                 {
     __provide_fill_ins = do_it;
 
     if (__simplicial_set != nullptr)
       __simplicial_set->setFillIns(__provide_fill_ins);
   }

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◆ clear()

void gum::DefaultEliminationSequenceStrategy::clear ( )

finalvirtual

clears the sequence (to prepare, for instance, a new elimination sequence)

Reimplemented from gum::EliminationSequenceStrategy.

Definition at line 146 of file defaultEliminationSequenceStrategy.cpp.

References __log_weights, __simplicial_set, and gum::EliminationSequenceStrategy::clear().

                                                  {
     UnconstrainedEliminationSequenceStrategy::clear();
 
     __log_weights.clear();
     if (__simplicial_set != nullptr) {
       delete __simplicial_set;
       __simplicial_set = nullptr;
     }
   }

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◆ copyFactory()

DefaultEliminationSequenceStrategy * gum::DefaultEliminationSequenceStrategy::copyFactory ( ) const

finalvirtual

virtual copy constructor

Warning: The newly created elimination sequence strategy points toward the same undirected graph as the one contained in the current strategy but each strategy possesses its own simplicial set. As a result, if both elimination strategies are used at the same time, they will probably result in a mess because their simplicial sets won't be synchronized correctly with the changing undirected graph. So, whenever using this virtual copy constructor, be sure that either the current or the newly created strategy is used for a triangulation but not both. This will necessarily be OK in DefaultTriangulations.

Implements gum::UnconstrainedEliminationSequenceStrategy.

Definition at line 110 of file defaultEliminationSequenceStrategy.cpp.

References DefaultEliminationSequenceStrategy().

                                                            {
     return new DefaultEliminationSequenceStrategy(*this);
   }

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◆ domainSizes()

INLINE const NodeProperty< Size > * gum::EliminationSequenceStrategy::domainSizes ( ) const

noexceptinherited

returns the current domain sizes

Definition at line 44 of file eliminationSequenceStrategy_inl.h.

References gum::EliminationSequenceStrategy::_domain_sizes.

                                                                        {
     return _domain_sizes;
   }

◆ eliminationUpdate()

void gum::DefaultEliminationSequenceStrategy::eliminationUpdate ( const NodeId node )

finalvirtual

performs all the graph/fill-ins updates provided (if any)

performs all the graph/fill-ins updates provided

Parameters

node	the node the elimination of which requires the graph update

Reimplemented from gum::EliminationSequenceStrategy.

Definition at line 215 of file defaultEliminationSequenceStrategy.cpp.

References __simplicial_set, gum::SimplicialSet::eraseClique(), and gum::SimplicialSet::makeClique().

                                                                             {
     if (__simplicial_set != nullptr) {
       __simplicial_set->makeClique(id);
       __simplicial_set->eraseClique(id);
     }
   }

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◆ fillIns()

const EdgeSet & gum::DefaultEliminationSequenceStrategy::fillIns ( )

finalvirtual

in case fill-ins are provided, this function returns the fill-ins due to all the nodes eliminated so far

in case fill-ins are provided, this function returns the fill-ins generated after the last node elimination

Reimplemented from gum::EliminationSequenceStrategy.

Definition at line 224 of file defaultEliminationSequenceStrategy.cpp.

References __provide_fill_ins, __simplicial_set, gum::EliminationSequenceStrategy::fillIns(), and gum::SimplicialSet::fillIns().

                                                              {
     if (!__provide_fill_ins || (__simplicial_set == nullptr))
       return UnconstrainedEliminationSequenceStrategy::fillIns();
     else
       return __simplicial_set->fillIns();
   }

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◆ graph()

INLINE UndiGraph * gum::EliminationSequenceStrategy::graph ( ) const

noexceptinherited

returns the current graph

Definition at line 37 of file eliminationSequenceStrategy_inl.h.

References gum::EliminationSequenceStrategy::_graph.

Referenced by gum::EliminationSequenceStrategy::setGraph().

                                                                       {
     return _graph;
   }

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◆ newFactory()

DefaultEliminationSequenceStrategy * gum::DefaultEliminationSequenceStrategy::newFactory ( ) const

finalvirtual

creates a new elimination sequence of the same type as the current object, but this sequence contains only an empty graph

Warning: you must deallocate by yourself the object returned

Returns: an empty clone of the current object with the same type

Implements gum::UnconstrainedEliminationSequenceStrategy.

Definition at line 103 of file defaultEliminationSequenceStrategy.cpp.

References __simplicial_ratio, __simplicial_threshold, and DefaultEliminationSequenceStrategy().

                                                           {
     return new DefaultEliminationSequenceStrategy(__simplicial_ratio,
                                                   __simplicial_threshold);
   }

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◆ nextNodeToEliminate()

NodeId gum::DefaultEliminationSequenceStrategy::nextNodeToEliminate ( )

finalvirtual

returns the new node to be eliminated within the triangulation algorithm

Exceptions

NotFound exception is thrown if there is no more node to eliminate in the graph

Implements gum::EliminationSequenceStrategy.

Definition at line 157 of file defaultEliminationSequenceStrategy.cpp.

References __log_weights, __simplicial_set, gum::EliminationSequenceStrategy::_graph, gum::SimplicialSet::bestAlmostSimplicialNode(), gum::SimplicialSet::bestQuasiSimplicialNode(), gum::SimplicialSet::bestSimplicialNode(), GUM_ERROR, gum::SimplicialSet::hasAlmostSimplicialNode(), gum::SimplicialSet::hasQuasiSimplicialNode(), and gum::SimplicialSet::hasSimplicialNode().

                                                                  {
     // if there is no simplicial set, send an exception
     if (_graph == nullptr) { GUM_ERROR(NotFound, "the graph is empty"); }
 
     // select a node to be eliminated: try simplicial nodes, then almost
     // simplicial nodes, then quasi-simplicial nodes
     // note that if __graph != 0, __simplicial_set has been allocated
     if (__simplicial_set->hasSimplicialNode())
       return __simplicial_set->bestSimplicialNode();
     else if (__simplicial_set->hasAlmostSimplicialNode())
       return __simplicial_set->bestAlmostSimplicialNode();
     else if (__simplicial_set->hasQuasiSimplicialNode())
       return __simplicial_set->bestQuasiSimplicialNode();
     else {
       // here: select the node through Kjaerulff's heuristic
       auto iter_heuristic = __log_weights.cbegin();
 
       if (iter_heuristic == __log_weights.cend())
         GUM_ERROR(NotFound, "there exists no more node to eliminate");
 
       double min_weight = iter_heuristic.val();
       NodeId removable_node = iter_heuristic.key();
       for (++iter_heuristic; iter_heuristic != __log_weights.cend();
            ++iter_heuristic) {
         if (iter_heuristic.val() < min_weight) {
           removable_node = iter_heuristic.key();
           min_weight = iter_heuristic.val();
         }
       }
 
       return removable_node;
     }
   }

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◆ providesFillIns()

bool gum::DefaultEliminationSequenceStrategy::providesFillIns ( ) const

finalvirtual

indicates whether the fill-ins generated by the eliminated nodes, if needed, will be computed by the elimination sequence, or need be computed by the triangulation itself.

indicates whether the new fill-ins generated by a new eliminated node, if needed, will be computed by the elimination sequence, or need be computed by the triangulation itself.

An elimination sequence provides fill-ins to its triangulation if and only if it has the ability to compute them and it has been asked to do so (by method askFillIns)

Implements gum::EliminationSequenceStrategy.

Definition at line 204 of file defaultEliminationSequenceStrategy.cpp.

References __provide_fill_ins.

                                                                  {
     return __provide_fill_ins;
   }

◆ providesGraphUpdate()

bool gum::DefaultEliminationSequenceStrategy::providesGraphUpdate ( ) const

finalvirtual

indicates whether the elimination sequence updates by itself the graph after a node has been eliminated

Some algorithms have more informations than the triangulation algorithm to update the graph after a node has been eliminated. They can thus exploit these informations to update the graph faster than the triangulation. Hence the latter should delegate this operation to the elimination sequence. This is the case, for instance, for the defaultEliminationSequence, which uses a SimplicialSet that knows that some eliminated nodes do not require any fill-in.

Implements gum::EliminationSequenceStrategy.

Definition at line 210 of file defaultEliminationSequenceStrategy.cpp.

                                                                      {
     return true;
   }

◆ setGraph()

bool gum::DefaultEliminationSequenceStrategy::setGraph	(	UndiGraph *	graph,
		const NodeProperty< Size > *	dom_sizes
	)

finalvirtual

sets a new graph to be triangulated

The elimination sequence algorithm reinitializes its data to start a new triangulation with Graph "graph"

Parameters

graph	the new graph to be triangulated
dom_sizes	the domain sizes of the variables/nodes

Returns: true if the data structures were modified (if the graph or the

Warning: Note that we allow dom_sizes to be defined over nodes/variables that do not belong to graph. These sizes will simply be ignored. However, it is compulsory that all the nodes of graph belong to dom_sizes; the graph is altered during the triangulation.; note that, by aGrUM's rule, the graph and the domain sizes are not copied but only referenced by the elimination sequence algorithm.

Reimplemented from gum::EliminationSequenceStrategy.

Definition at line 135 of file defaultEliminationSequenceStrategy.cpp.

References __createSimplicialSet(), and gum::EliminationSequenceStrategy::setGraph().

Referenced by DefaultEliminationSequenceStrategy().

                                                                  {
     if (UnconstrainedEliminationSequenceStrategy::setGraph(graph, domain_sizes)) {
       __createSimplicialSet();
       return true;
     }
 
     return false;
   }

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Member Data Documentation

◆ __log_weights

NodeProperty< double > gum::DefaultEliminationSequenceStrategy::__log_weights

private

for each node, the weight of the clique created by the node's elimination

Definition at line 223 of file defaultEliminationSequenceStrategy.h.

Referenced by __createSimplicialSet(), clear(), DefaultEliminationSequenceStrategy(), and nextNodeToEliminate().

◆ __provide_fill_ins

bool gum::DefaultEliminationSequenceStrategy::__provide_fill_ins {false}

private

indicates whether we compute new fill-ins

Definition at line 235 of file defaultEliminationSequenceStrategy.h.

Referenced by __createSimplicialSet(), askFillIns(), fillIns(), and providesFillIns().

◆ __simplicial_ratio

double gum::DefaultEliminationSequenceStrategy::__simplicial_ratio

private

the ratio used by __simplicial_set for its quasi-simplicial nodes

Definition at line 229 of file defaultEliminationSequenceStrategy.h.

Referenced by __createSimplicialSet(), and newFactory().

◆ __simplicial_set

SimplicialSet* gum::DefaultEliminationSequenceStrategy::__simplicial_set {nullptr}

private

the simplicial set used for determining the best nodes to eliminate

Definition at line 226 of file defaultEliminationSequenceStrategy.h.

Referenced by __createSimplicialSet(), askFillIns(), clear(), DefaultEliminationSequenceStrategy(), eliminationUpdate(), fillIns(), nextNodeToEliminate(), and ~DefaultEliminationSequenceStrategy().

◆ __simplicial_threshold

double gum::DefaultEliminationSequenceStrategy::__simplicial_threshold

private

the threshold used by __simplicial_set to determine small cliques

Definition at line 232 of file defaultEliminationSequenceStrategy.h.

Referenced by __createSimplicialSet(), and newFactory().

◆ _domain_sizes

const NodeProperty< Size >* gum::EliminationSequenceStrategy::_domain_sizes {nullptr}

protectedinherited

the domain sizes of the variables/nodes

Definition at line 159 of file eliminationSequenceStrategy.h.

Referenced by gum::EliminationSequenceStrategy::clear(), gum::EliminationSequenceStrategy::domainSizes(), and gum::EliminationSequenceStrategy::setGraph().

◆ _graph

UndiGraph* gum::EliminationSequenceStrategy::_graph {nullptr}

protectedinherited

the graph to be triangulated

Definition at line 156 of file eliminationSequenceStrategy.h.

◆ _log_domain_sizes

NodeProperty< double > gum::EliminationSequenceStrategy::_log_domain_sizes

protectedinherited

the log of the domain sizes of the variables/nodes

Definition at line 162 of file eliminationSequenceStrategy.h.

Referenced by __createSimplicialSet(), gum::DefaultPartialOrderedEliminationSequenceStrategy::__createSimplicialSet(), gum::EliminationSequenceStrategy::clear(), and gum::EliminationSequenceStrategy::setGraph().

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

agrum/graphs/algorithms/triangulations/eliminationStrategies/defaultEliminationSequenceStrategy.h
agrum/graphs/algorithms/triangulations/eliminationStrategies/defaultEliminationSequenceStrategy.cpp

Public Member Functions

Protected Attributes

Detailed Description

the nodes that are simplicial (i.e., those that already form a clique

then the nodes that are almost simplicial (i.e., if we remove one of

are eliminated

the quasi simplicial nodes (i.e., the nodes that do not require many

finally, the heuristic proposed by Kjaerulff(90) is used to compute the

Constructor & Destructor Documentation

◆ DefaultEliminationSequenceStrategy() [1/4]

◆ DefaultEliminationSequenceStrategy() [2/4]

◆ DefaultEliminationSequenceStrategy() [3/4]

◆ DefaultEliminationSequenceStrategy() [4/4]

◆ ~DefaultEliminationSequenceStrategy()

Member Function Documentation

◆ __createSimplicialSet()

◆ askFillIns()

◆ clear()

◆ copyFactory()

◆ domainSizes()

◆ eliminationUpdate()

◆ fillIns()

◆ graph()

◆ newFactory()

◆ nextNodeToEliminate()

◆ providesFillIns()

◆ providesGraphUpdate()

◆ setGraph()

Member Data Documentation

◆ __log_weights

◆ __provide_fill_ins

◆ __simplicial_ratio

◆ __simplicial_set

◆ __simplicial_threshold

◆ _domain_sizes

◆ _graph

◆ _log_domain_sizes