unconstrainedEliminationSequenceStrategy.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 Base Class for all elimination sequence algorithms that require only
 * the graph to be triangulated and the nodes' domain sizes to produce the node
 * elimination ordering.
 *
 * In many cases, the graph to be triangulated and the nodes domain sizes are
 * the only information needed to compute an elimination ordering. For instance,
 * this is only what is needed for computing junction trees for Bayesian
 * networks or GAI networks. For such cases, the elimination sequence algorithms
 * derived from UnconstrainedEliminationSequenceStrategy are appropriate. There
 * are however other cases in which additional informations must be passed to
 * the elimination sequence algorithm to produce a correct elimination ordering.
 * For instance, computing a strong junction tree for an influence diagram
 * requires the knowledge of a partial ordering on the nodes to be eliminated.
 * For such cases, classes derived from UnconstrainedEliminationSequenceStrategy
 * are not appropriate and those should be derived from other elimination
 * sequence
 * factories, for from instance PartialOrderedEliminationSequenceStrategy.
 *
 * @author Christophe GONZALES(@AMU) and Pierre-Henri WUILLEMIN(@LIP6)
 */

#ifndef GUM_UNCONSTRAINED_ELIMINATION_SEQUENCE_STRATEGY_H
#define GUM_UNCONSTRAINED_ELIMINATION_SEQUENCE_STRATEGY_H

#include <agrum/tools/graphs/algorithms/triangulations/eliminationStrategies/eliminationSequenceStrategy.h>

namespace gum {

  /** @class UnconstrainedEliminationSequenceStrategy
   * @brief The base class for all elimination sequence algorithms that require
   * only the graph to be triangulated and the nodes' domain sizes to produce
   * the node elimination ordering.
   *
   * \ingroup graph_group
   *
   */
  class UnconstrainedEliminationSequenceStrategy: public EliminationSequenceStrategy {
    public:
    // ############################################################################
    /// @name Constructors / Destructors
    // ############################################################################
    /// @{

    /// destructor
    virtual ~UnconstrainedEliminationSequenceStrategy();

    /** @brief 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
     * @return an empty clone of the current object with the same type */
    virtual UnconstrainedEliminationSequenceStrategy* newFactory() const = 0;

    /// virtual copy constructor
    virtual UnconstrainedEliminationSequenceStrategy* copyFactory() const = 0;

    /// @}


    protected:
    // ############################################################################
    /// @name Constructors / Destructors
    // ############################################################################
    /// @{

    /// default constructor
    UnconstrainedEliminationSequenceStrategy();

    /// constructor for an a priori non empty graph
    /** @param graph the graph to be triangulated, i.e., the nodes of which will
     * be eliminated
     * @param dom_sizes the domain sizes of the nodes to be eliminated
     * @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 the graph is altered during the triangulation.
     * @warning note that, by aGrUM's rule, the graph and the domain sizes are
     * not copied but only referenced by the elimination sequence algorithm. */
    UnconstrainedEliminationSequenceStrategy(UndiGraph*                  graph,
                                             const NodeProperty< Size >* dom_sizes);

    /// copy constructor
    UnconstrainedEliminationSequenceStrategy(const UnconstrainedEliminationSequenceStrategy&);

    /// move constructor
    UnconstrainedEliminationSequenceStrategy(UnconstrainedEliminationSequenceStrategy&&);

    /// @}
  };

} /* namespace gum */

#endif /* GUM_UNCONSTRAINED_ELIMINATION_SEQUENCE_STRATEGY_H */