orderedTriangulation.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 class for graph triangulations for which we enforce a given complete
 * ordering on the nodes eliminations.
 *
 * @author Christophe GONZALES(@AMU) and Pierre-Henri WUILLEMIN(@LIP6)
 */
#ifndef GUM_ORDERED_TRIANGULATION_H
#define GUM_ORDERED_TRIANGULATION_H

#include <vector>

#include <agrum/tools/graphs/algorithms/triangulations/eliminationStrategies/orderedEliminationSequenceStrategy.h>
#include <agrum/tools/graphs/algorithms/triangulations/junctionTreeStrategies/defaultJunctionTreeStrategy.h>
#include <agrum/tools/graphs/algorithms/triangulations/staticTriangulation.h>

namespace gum {


  /** @class OrderedTriangulation
   * @brief class for graph triangulations for which we enforce a given complete
   * ordering on the nodes eliminations.
   *
   * \ingroup graph_group
   *
   */
  class OrderedTriangulation: public StaticTriangulation {
    public:
    // ############################################################################
    /// @name Constructors / Destructors
    // ############################################################################
    /// @{

    /// default constructor
    /** @param elimSeq the elimination sequence used to triangulate the graph
     * @param JTStrategy the junction tree strategy used to create junction
     * trees
     * @param minimality a Boolean indicating whether we should enforce that
     * the triangulation is minimal w.r.t. inclusion */
    OrderedTriangulation(const OrderedEliminationSequenceStrategy& elimSeq
                         = OrderedEliminationSequenceStrategy(),
                         const JunctionTreeStrategy& JTStrategy = DefaultJunctionTreeStrategy(),
                         bool                        minimality = false);

    /// constructor with a given graph
    /** @param graph the graph to be triangulated, i.e., the nodes of which will
     * be eliminated
     * @param domsizes the domain sizes of the nodes to be eliminated
     * @param sequence  the order in which the nodes should be eliminated
     * @param elimSeq the elimination sequence used to triangulate the graph.
     * Only a reference/pointer to the sequence passed in argument is kept in
     * the current class.
     * @param JTStrategy the junction tree strategy used to create junction
     * trees
     * @param minimality a Boolean indicating whether we should enforce that
     * the triangulation is minimal w.r.t. inclusion
     * @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
     * @warning note that, by aGrUM's rule, the graph, the domain sizes and the
     * elimination sequence are not copied but only referenced by the
     * triangulation algorithm. */
    OrderedTriangulation(const UndiGraph*                          graph,
                         const NodeProperty< Size >*               domsizes,
                         const std::vector< NodeId >*              sequence,
                         const OrderedEliminationSequenceStrategy& elimSeq
                         = OrderedEliminationSequenceStrategy(),
                         const JunctionTreeStrategy& JTStrategy = DefaultJunctionTreeStrategy(),
                         bool                        minimality = false);

    /// copy constructor
    OrderedTriangulation(const OrderedTriangulation& from);

    /// move constructor
    OrderedTriangulation(OrderedTriangulation&& from);

    /** @brief returns a fresh triangulation over the same graph and of the same
     * type as the current object (using the same sequence, etc.)
     *
     * note that we return a pointer as it enables subclasses to return
     * pointers to their types, not Triangulation pointers. See item 25 of the
     * more effective C++.*/
    virtual OrderedTriangulation* newFactory() const final;

    /// virtual copy constructor
    virtual OrderedTriangulation* copyFactory() const final;

    /// destructor
    virtual ~OrderedTriangulation();

    /// @}

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

    /// initialize the triangulation data structures for a new graph
    /** @param graph the graph to be triangulated, i.e., the nodes of which will
     * be eliminated
     * @param domsizes the domain sizes of the nodes to be eliminated
     * @param sequence  the order in which the nodes should be eliminated
     * @warning note that, by aGrUM's rule, the graph and the domain sizes are
     * not
     *  notcopied but only referenced by the triangulation algorithm. */
    virtual void setGraph(const UndiGraph* graph, const NodeProperty< Size >* domsizes) final;

    /// sets the sequence of elimination (only the reference is stored)
    /** The elimination sequence is kept outside this class for efficiency
     * reasons. */
    virtual void setOrder(const std::vector< NodeId >* order) final;

    /// @}

    protected:
    /// the function called to initialize the triangulation process
    /** This function is called when the triangulation process starts and is
     * used to initialize the elimination sequence strategy. Actually, the
     * graph that is modified by the triangulation algorithm is a copy of
     * the original graph, and this copy need be known by the elimination
     * sequence strategy. initTriangulation_ is used to transmit this
     * knowledge to the elimination sequence (through method setGraph of the
     * elimination sequence class).
     * @param graph the very graph that is triangulated (this is a copy of
     * original_graph_) */
    virtual void initTriangulation_(UndiGraph& graph) final;


    /// the elimination sequence to apply
    /** @warning  _order_ is not owned by the orderedTriangulation class */
    const std::vector< NodeId >* _order_{nullptr};

    /// @}

    private:
    /// forbid copy operator
    OrderedTriangulation& operator=(const OrderedTriangulation&);
  };

} /* namespace gum */

#endif /* GUM_ORDERED_TRIANGULATION_H */