binaryJoinTreeConverterDefault.h

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/**
 *
 *   Copyright (c) 2005-2021 by Pierre-Henri WUILLEMIN(@LIP6) & Christophe GONZALES(@AMU)
 *   info_at_agrum_dot_org
 *
 *  This library is free software: you can redistribute it and/or modify
 *  it under the terms of the GNU Lesser General Public License as published by
 *  the Free Software Foundation, either version 3 of the License, or
 *  (at your option) any later version.
 *
 *  This library is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU Lesser General Public License for more details.
 *
 *  You should have received a copy of the GNU Lesser General Public License
 *  along with this library.  If not, see <http://www.gnu.org/licenses/>.
 *
 */


/** @file
 * @brief An algorithm for converting a join tree into a binary join tree
 *
 * @author Christophe GONZALES(@AMU) and Pierre-Henri WUILLEMIN(@LIP6)
 */
#ifndef GUM_BINARY_JOIN_TREE_CONVERTER_DEFAULT_H
#define GUM_BINARY_JOIN_TREE_CONVERTER_DEFAULT_H

#include <agrum/tools/graphs/algorithms/binaryJoinTreeConverter.h>

namespace gum {

  class BinaryJoinTreeConverterDefault {
    public:
    // ############################################################################
    /// @name Constructors / Destructors
    // ############################################################################
    /// @{

    /// default constructor
    BinaryJoinTreeConverterDefault();

    /// destructor
    virtual ~BinaryJoinTreeConverterDefault();

    /// @}

    // ############################################################################
    /// @name Accessors/Modifiers
    // ############################################################################
    /// @{

    /// returns a binary join tree corresponding to clique graph JT
    /** This method creates and returns a new binary join tree compatible with
     * that passed in argument (JT) and optimized for inference. As such, this
     * requires knowing the join tree to be converted (of course), but also
     * which roots will be used by the collect/diffusion inference engine and
     * the domain size of the variables contained in the cliques of JT (to
     * optimize the combination of the potentials contained in the cliques.
     * @throws InvalidNode exception is thrown if some roots do not belong to
     * JT or if several roots belong to the same connected component.
     * @warning If you do not pass in argument a root for each connected
     * component,
     * then for those with unspecified roots, an arbitrary root will be computed
     * and used for the binarization. */
    CliqueGraph convert(const CliqueGraph&          JT,
                        const NodeProperty< Size >& domain_sizes,
                        const NodeSet&              roots);

    /// returns all the roots considered for all the connected components
    const NodeSet& roots() const;

    /// @}

    private:
    /// the new roots that have been created to compute the last query
    NodeSet _roots_;

    /// forbid copy constructor
    BinaryJoinTreeConverterDefault(const BinaryJoinTreeConverterDefault&);

    /// forbid copy operator
    BinaryJoinTreeConverterDefault& operator=(const BinaryJoinTreeConverterDefault&);

    /** @brief a function used to mark the nodes belonging to a given
     * connected component */
    void _markConnectedComponent_(const CliqueGraph&    JT,
                                  NodeId                root,
                                  NodeProperty< bool >& mark) const;

    /// convert a whole connected component into a binary join tree
    void _convertConnectedComponent_(CliqueGraph&                JT,
                                     NodeId                      current_node,
                                     NodeId                      from,
                                     const NodeProperty< Size >& domain_sizes,
                                     NodeProperty< bool >&       mark) const;

    /// convert a clique and its adjacent cliques into a binary join tree
    void _convertClique_(CliqueGraph&                JT,
                         NodeId                      clique,
                         NodeId                      from,
                         const NodeProperty< Size >& domain_sizes) const;

    /// returns the domain size of the union of two cliques
    float _combinedSize_(const NodeSet&              nodes1,
                         const NodeSet&              nodes2,
                         const NodeProperty< Size >& domain_sizes) const;
  };

} /* namespace gum */

#endif /* GUM_BINARY_JOIN_TREE_CONVERTER_DEFAULT_H */