1 /* This file is part of libDAI - http://www.libdai.org/
2 *
4 * 2, or (at your option) any later version. libDAI is distributed without any
5 * warranty. See the file COPYING for more details.
6 *
7 * Copyright (C) 2006-2009 Joris Mooij [joris dot mooij at libdai dot org]
8 * Copyright (C) 2006-2007 Radboud University Nijmegen, The Netherlands
9 */
12 /// \file
13 /// \brief Defines classes Region, FRegion and RegionGraph.
16 #ifndef __defined_libdai_regiongraph_h
17 #define __defined_libdai_regiongraph_h
20 #include <iostream>
21 #include <dai/bipgraph.h>
22 #include <dai/factorgraph.h>
23 #include <dai/weightedgraph.h>
26 namespace dai {
29 /// A Region is a set of variables with a counting number
30 class Region : public VarSet {
31 private:
32 /// Counting number
33 double _c;
35 public:
36 /// Default constructor
37 Region() : VarSet(), _c(1.0) {}
39 /// Construct from a set of variables and a counting number
40 Region(const VarSet &x, double c) : VarSet(x), _c(c) {}
42 /// Returns constant reference to counting number
43 const double & c() const { return _c; }
45 /// Returns reference to counting number
46 double & c() { return _c; }
47 };
50 /// An FRegion is a factor with a counting number
51 class FRegion : public Factor {
52 private:
53 /// Counting number
54 double _c;
56 public:
57 /// Default constructor
58 FRegion() : Factor(), _c(1.0) {}
60 /// Constructs from a factor and a counting number
61 FRegion( const Factor & x, double c ) : Factor(x), _c(c) {}
63 /// Returns constant reference to counting number
64 const double & c() const { return _c; }
66 /// Returns reference to counting number
67 double & c() { return _c; }
68 };
71 /// A RegionGraph combines a bipartite graph consisting of outer regions (type FRegion) and inner regions (type Region) with a FactorGraph
72 /** A RegionGraph inherits from a FactorGraph and adds additional structure in the form of a "region graph". Our definition of region graph
73 * is inspired by [\ref HAK03], which is less general than the definition given in [\ref YFW05].
74 *
75 * The extra structure described by a RegionGraph over that described by a FactorGraph is:
76 * - a set of outer regions (indexed by \f$\alpha\f$), where each outer region consists of
77 * - a factor defined on a subset of variables
78 * - a counting number
79 * - a set of inner regions (indexed by \f$\beta\f$), where each inner region consists of
80 * - a subset of variables
81 * - a counting number
82 * - edges between inner and outer regions
83 *
84 * Each factor in the factor graph belongs to an outer region; normally, the factor contents
85 * of an outer region would be the product of all the factors that belong to that region.
86 */
87 class RegionGraph : public FactorGraph {
88 public:
89 /// Stores the neighborhood structure
90 BipartiteGraph G;
92 /// The outer regions (corresponding to nodes of type 1)
93 std::vector<FRegion> ORs;
95 /// The inner regions (corresponding to nodes of type 2)
96 std::vector<Region> IRs;
98 /// Stores for each factor index the index of the outer region it belongs to
99 std::vector<size_t> fac2OR;
102 public:
103 /// \name Constructors and destructors
104 //@{
105 /// Default constructor
106 RegionGraph() : FactorGraph(), G(), ORs(), IRs(), fac2OR() {}
108 /// Partially constructs a region graph from a factor graph
109 RegionGraph( const FactorGraph &fg ) : FactorGraph(fg), G(), ORs(), IRs(), fac2OR() {}
111 /// Constructs a region graph from a factor graph, a vector of outer regions, a vector of inner regions and a vector of edges
112 /** The counting numbers for the outer regions are set to 1.
113 */
114 RegionGraph( const FactorGraph &fg, const std::vector<Region> &ors, const std::vector<Region> &irs, const std::vector<std::pair<size_t,size_t> > &edges );
116 /// Constructs a region graph from a factor graph and a vector of outer clusters (CVM style)
117 /** The region graph is constructed as in the Cluster Variation Method.
118 *
119 * The outer regions have as variable subsets the clusters specified in \a cl.
120 * Each factor in the factor graph \a fg is assigned to one of the outer regions.
121 * Each outer region gets counting number 1.
122 *
123 * The inner regions are (repeated) intersections of outer regions.
124 * An inner and an outer region are connected if the variables in the inner region form a
125 * subset of the variables in the outer region. The counting numbers for the inner
126 * regions are calculated by calcCountingNumbers() and satisfy the Moebius formula.
127 */
128 RegionGraph( const FactorGraph &fg, const std::vector<VarSet> &cl );
130 /// Clone \c *this (virtual copy constructor)
131 virtual RegionGraph* clone() const { return new RegionGraph(*this); }
132 //@}
134 /// \name Queries
135 //@{
136 /// Returns number of outer regions
137 size_t nrORs() const { return ORs.size(); }
138 /// Returns number of inner regions
139 size_t nrIRs() const { return IRs.size(); }
141 /// Returns constant reference to outer region \a alpha
142 const FRegion & OR(size_t alpha) const { return ORs[alpha]; }
143 /// Returns reference to outer region \a alpha
144 FRegion & OR(size_t alpha) { return ORs[alpha]; }
146 /// Returns constant reference to inner region \a beta
147 const Region & IR(size_t beta) const { return IRs[beta]; }
148 /// Returns reference to inner region \a beta
149 Region & IR(size_t beta) { return IRs[beta]; }
151 /// Returns constant reference to the neighbors of outer region \a alpha
152 const Neighbors & nbOR( size_t alpha ) const { return G.nb1(alpha); }
153 /// Returns constant reference to the neighbors of inner region \a beta
154 const Neighbors & nbIR( size_t beta ) const { return G.nb2(beta); }
156 /// Check whether the counting numbers are valid
157 /** Counting numbers are said to be (variable) valid if for each variable \f$x\f$,
158 * \f[\sum_{\alpha \ni x} c_\alpha + \sum_{\beta \ni x} c_\beta = 1\f]
159 * or in words, if the sum of the counting numbers of the regions
160 * that contain the variable equals one.
161 */
162 bool checkCountingNumbers() const;
164 // OBSOLETE
165 /// For backwards compatibility (to be removed soon)
166 bool Check_Counting_Numbers() { return checkCountingNumbers(); }
167 //@}
169 /// \name Operations
170 //@{
171 /// Set the content of the \a I 'th factor and make a backup of its old content if \a backup == \c true
172 virtual void setFactor( size_t I, const Factor &newFactor, bool backup = false ) {
173 FactorGraph::setFactor( I, newFactor, backup );
174 RecomputeOR( I );
175 }
177 /// Set the contents of all factors as specified by \a facs and make a backup of the old contents if \a backup == \c true
178 virtual void setFactors( const std::map<size_t, Factor> & facs, bool backup = false ) {
179 FactorGraph::setFactors( facs, backup );
180 VarSet ns;
181 for( std::map<size_t, Factor>::const_iterator fac = facs.begin(); fac != facs.end(); fac++ )
182 ns |= fac->second.vars();
183 RecomputeORs( ns );
184 }
186 /// Recompute all outer regions
187 /** The factor contents of each outer region is set to the product of the factors belonging to that region.
188 */
189 void RecomputeORs();
191 /// Recompute all outer regions involving the variables in \a vs
192 /** The factor contents of each outer region involving at least one of the variables in \a vs is set to the product of the factors belonging to that region.
193 */
194 void RecomputeORs( const VarSet &vs );
196 /// Recompute all outer regions involving factor \a I
197 /** The factor contents of each outer region involving the \a I 'th factor is set to the product of the factors belonging to that region.
198 */
199 void RecomputeOR( size_t I );
201 /// Calculates counting numbers of inner regions based upon counting numbers of outer regions
202 /** The counting numbers of the inner regions are set using the Moebius inversion formula:
203 * \f[ c_\beta := 1 - \sum_{\gamma \in \mathrm{an}(\beta)} c_\gamma \f]
204 * where \f$\mathrm{an}(\beta)\f$ are the ancestors of inner region \f$\beta\f$ according to
205 * the partial ordering induced by the subset relation (i.e., a region is a child of another
206 * region if its variables are a subset of the variables of its parent region).
207 */
208 void calcCountingNumbers();
210 // OBSOLETE
211 /// For backwards compatibility (to be removed soon)
212 void Calc_Counting_Numbers() { calcCountingNumbers(); }
213 //@}
215 /// \name Input/output
216 //@{
217 /// Writes a RegionGraph to an output stream
218 friend std::ostream & operator << ( std::ostream & os, const RegionGraph & rg );
219 //@}
220 };
223 } // end of namespace dai
226 #endif