Improved documentation of include/dai/bp.h
[libdai.git] / include / dai / regiongraph.h
1 /* This file is part of libDAI - http://www.libdai.org/
2 *
3 * libDAI is licensed under the terms of the GNU General Public License version
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 */
10
11
12 /// \file
13 /// \brief Defines classes Region, FRegion and RegionGraph.
14
15
16 #ifndef __defined_libdai_regiongraph_h
17 #define __defined_libdai_regiongraph_h
18
19
20 #include <iostream>
21 #include <dai/bipgraph.h>
22 #include <dai/factorgraph.h>
23 #include <dai/weightedgraph.h>
24
25
26 namespace dai {
27
28
29 /// A Region is a set of variables with a counting number
30 class Region : public VarSet {
31 private:
32 /// Counting number
33 Real _c;
34
35 public:
36 /// Default constructor
37 Region() : VarSet(), _c(1.0) {}
38
39 /// Construct from a set of variables and a counting number
40 Region(const VarSet &x, Real c) : VarSet(x), _c(c) {}
41
42 /// Returns constant reference to counting number
43 const Real & c() const { return _c; }
44
45 /// Returns reference to counting number
46 Real & c() { return _c; }
47 };
48
49
50 /// An FRegion is a factor with a counting number
51 class FRegion : public Factor {
52 private:
53 /// Counting number
54 Real _c;
55
56 public:
57 /// Default constructor
58 FRegion() : Factor(), _c(1.0) {}
59
60 /// Constructs from a factor and a counting number
61 FRegion( const Factor & x, Real c ) : Factor(x), _c(c) {}
62
63 /// Returns constant reference to counting number
64 const Real & c() const { return _c; }
65
66 /// Returns reference to counting number
67 Real & c() { return _c; }
68 };
69
70
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;
91
92 /// The outer regions (corresponding to nodes of type 1)
93 std::vector<FRegion> ORs;
94
95 /// The inner regions (corresponding to nodes of type 2)
96 std::vector<Region> IRs;
97
98 /// Stores for each factor index the index of the outer region it belongs to
99 std::vector<size_t> fac2OR;
100
101
102 public:
103 /// \name Constructors and destructors
104 //@{
105 /// Default constructor
106 RegionGraph() : FactorGraph(), G(), ORs(), IRs(), fac2OR() {}
107
108 /// Partially constructs a region graph from a factor graph
109 RegionGraph( const FactorGraph &fg ) : FactorGraph(fg), G(), ORs(), IRs(), fac2OR() {}
110
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 );
115
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 );
129
130 /// Clone \c *this (virtual copy constructor)
131 virtual RegionGraph* clone() const { return new RegionGraph(*this); }
132 //@}
133
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(); }
140
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]; }
145
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]; }
150
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); }
155
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;
163
164 // OBSOLETE
165 /// Check whether the counting numbers are valid
166 /** \deprecated Renamed into dai::RegionGraph::checkCountingNumbers()
167 */
168 bool Check_Counting_Numbers() { return checkCountingNumbers(); }
169 //@}
170
171 /// \name Operations
172 //@{
173 /// Set the content of the \a I 'th factor and make a backup of its old content if \a backup == \c true
174 virtual void setFactor( size_t I, const Factor &newFactor, bool backup = false ) {
175 FactorGraph::setFactor( I, newFactor, backup );
176 RecomputeOR( I );
177 }
178
179 /// Set the contents of all factors as specified by \a facs and make a backup of the old contents if \a backup == \c true
180 virtual void setFactors( const std::map<size_t, Factor> & facs, bool backup = false ) {
181 FactorGraph::setFactors( facs, backup );
182 VarSet ns;
183 for( std::map<size_t, Factor>::const_iterator fac = facs.begin(); fac != facs.end(); fac++ )
184 ns |= fac->second.vars();
185 RecomputeORs( ns );
186 }
187
188 /// Recompute all outer regions
189 /** The factor contents of each outer region is set to the product of the factors belonging to that region.
190 */
191 void RecomputeORs();
192
193 /// Recompute all outer regions involving the variables in \a vs
194 /** 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.
195 */
196 void RecomputeORs( const VarSet &vs );
197
198 /// Recompute all outer regions involving factor \a I
199 /** 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.
200 */
201 void RecomputeOR( size_t I );
202
203 /// Calculates counting numbers of inner regions based upon counting numbers of outer regions
204 /** The counting numbers of the inner regions are set using the Moebius inversion formula:
205 * \f[ c_\beta := 1 - \sum_{\gamma \in \mathrm{an}(\beta)} c_\gamma \f]
206 * where \f$\mathrm{an}(\beta)\f$ are the ancestors of inner region \f$\beta\f$ according to
207 * the partial ordering induced by the subset relation (i.e., a region is a child of another
208 * region if its variables are a subset of the variables of its parent region).
209 */
210 void calcCountingNumbers();
211
212 // OBSOLETE
213 /// Calculates counting numbers of inner regions based upon counting numbers of outer regions
214 /** \deprecated Renamed into dai::RegionGraph::calcCountingNumbers()
215 */
216 void Calc_Counting_Numbers() { calcCountingNumbers(); }
217 //@}
218
219 /// \name Input/output
220 //@{
221 /// Writes a RegionGraph to an output stream
222 friend std::ostream & operator << ( std::ostream & os, const RegionGraph & rg );
223 //@}
224 };
225
226
227 } // end of namespace dai
228
229
230 #endif