88 lines
2.8 KiB
C++
88 lines
2.8 KiB
C++
/* ----------------------------------------------------------------------------
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* GTSAM Copyright 2010, Georgia Tech Research Corporation,
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* Atlanta, Georgia 30332-0415
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* All Rights Reserved
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* Authors: Frank Dellaert, et al. (see THANKS for the full author list)
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* See LICENSE for the license information
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* -------------------------------------------------------------------------- */
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/*
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* JunctionTree.h
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* Created on: Feb 4, 2010
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* @Author: Kai Ni
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* @Author: Frank Dellaert
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* @brief: The junction tree
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*/
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#pragma once
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#include <set>
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#include <vector>
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#include <list>
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#include <boost/shared_ptr.hpp>
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#include <gtsam/base/FastList.h>
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#include <gtsam/inference/BayesTree.h>
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#include <gtsam/inference/ClusterTree.h>
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#include <gtsam/inference/IndexConditional.h>
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namespace gtsam {
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/**
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* A junction tree (or clique-tree) is a cluster-tree where each node k represents a
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* clique (maximal fully connected subset) of an associated chordal graph, such as a
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* chordal Bayes net resulting from elimination. In GTSAM the BayesTree is used to
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* represent the clique tree associated with a Bayes net, and the JunctionTree is
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* used to collect the factors associated with each clique during the elimination process.
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*/
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template<class FG>
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class JunctionTree: public ClusterTree<FG> {
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public:
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// In a junction tree each cluster is associated with a clique
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typedef typename ClusterTree<FG>::Cluster Clique;
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typedef typename Clique::shared_ptr sharedClique;
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typedef class BayesTree<typename FG::Factor::Conditional> BayesTree;
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typedef boost::shared_ptr<JunctionTree<FG> > shared_ptr;
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// And we will frequently refer to a symbolic Bayes tree
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typedef gtsam::BayesTree<IndexConditional> SymbolicBayesTree;
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private:
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// distribute the factors along the cluster tree
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sharedClique distributeFactors(const FG& fg,
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const SymbolicBayesTree::sharedClique& clique);
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// distribute the factors along the cluster tree
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sharedClique distributeFactors(const FG& fg, const std::vector<FastList<size_t> >& targets,
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const SymbolicBayesTree::sharedClique& clique);
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// recursive elimination function
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std::pair<typename BayesTree::sharedClique, typename FG::sharedFactor>
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eliminateOneClique(const boost::shared_ptr<const Clique>& clique) const;
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// internal constructor
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void construct(const FG& fg, const VariableIndex& variableIndex);
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public:
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/** Default constructor */
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JunctionTree() {}
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/** Construct from a factor graph. Computes a variable index. */
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JunctionTree(const FG& fg);
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/** Construct from a factor graph and a pre-computed variable index. */
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JunctionTree(const FG& fg, const VariableIndex& variableIndex);
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// eliminate the factors in the subgraphs
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typename BayesTree::sharedClique eliminate() const;
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}; // JunctionTree
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} // namespace gtsam
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