Some documentation improvements
[libdai.git] / include / dai / mr.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) 2007 Bastian Wemmenhove
8 * Copyright (C) 2007-2009 Joris Mooij [joris dot mooij at libdai dot org]
9 * Copyright (C) 2007 Radboud University Nijmegen, The Netherlands
10 */
11
12
13 /// \file
14 /// \brief Defines class MR, which implements loop corrections as proposed by Montanari and Rizzo
15
16
17 #ifndef __defined_libdai_mr_h
18 #define __defined_libdai_mr_h
19
20
21 #include <vector>
22 #include <string>
23 #include <dai/factorgraph.h>
24 #include <dai/daialg.h>
25 #include <dai/enum.h>
26 #include <dai/properties.h>
27 #include <dai/exceptions.h>
28 #include <boost/dynamic_bitset.hpp>
29
30
31 namespace dai {
32
33
34 /// Approximate inference algorithm by Montanari and Rizzo [\ref MoR05]
35 /** \author Bastian Wemmenhove wrote the original implementation before it was merged into libDAI
36 */
37 class MR : public DAIAlgFG {
38 private:
39 /// Is the underlying factor graph supported?
40 bool supported;
41 /// con[i] = connectivity of spin \a i
42 std::vector<size_t> con;
43 /// nb[i] are the neighbours of spin \a i
44 std::vector<std::vector<size_t> > nb;
45 /// tJ[i][_j] is the hyperbolic tangent of the interaction between spin \a i and its neighbour nb[i][_j]
46 std::vector<std::vector<Real> > tJ;
47 /// theta[i] is the local field on spin \a i
48 std::vector<Real> theta;
49 /// M[i][_j] is \f$ M^{(i)}_j \f$
50 std::vector<std::vector<Real> > M;
51 /// The \a _j 'th neighbour of spin \a i has spin \a i as its kindex[i][_j]'th neighbour
52 std::vector<std::vector<size_t> > kindex;
53 /// Cavity correlations
54 std::vector<std::vector<std::vector<Real> > > cors;
55 /// Maximum connectivity
56 static const size_t kmax = 31;
57 /// Type used for managing a subset of neighbors
58 typedef boost::dynamic_bitset<> sub_nb;
59 /// Number of variables (spins)
60 size_t N;
61 /// Magnetizations
62 std::vector<Real> Mag;
63 /// Maximum difference encountered so far
64 Real _maxdiff;
65 /// Number of iterations needed
66 size_t _iters;
67
68 public:
69 /// Parameters for MR
70 struct Properties {
71 /// Enumeration of different types of update equations
72 /** The possible update equations are:
73 * - FULL full updates, slow but accurate
74 * - LINEAR linearized updates, faster but less accurate
75 */
76 DAI_ENUM(UpdateType,FULL,LINEAR);
77
78 /// Enumeration of different ways of initializing the cavity correlations
79 /** The possible cavity initializations are:
80 * - RESPPROP using response propagation ("linear response")
81 * - CLAMPING using clamping and BP
82 * - EXACT using JunctionTree
83 */
84 DAI_ENUM(InitType,RESPPROP,CLAMPING,EXACT);
85
86 /// Verbosity (amount of output sent to stderr)
87 size_t verbose;
88
89 /// Tolerance for convergence test
90 Real tol;
91
92 /// Update equations
93 UpdateType updates;
94
95 /// How to initialize the cavity correlations
96 InitType inits;
97 } props;
98
99 /// Name of this inference method
100 static const char *Name;
101
102 public:
103 /// Default constructor
104 MR() : DAIAlgFG(), supported(), con(), nb(), tJ(), theta(), M(), kindex(), cors(), N(), Mag(), _maxdiff(), _iters(), props() {}
105
106 /// Construct from FactorGraph \a fg and PropertySet \a opts
107 /** \param opts Parameters @see Properties
108 * \note This implementation only deals with binary variables and pairwise interactions.
109 * \throw NOT_IMPLEMENTED if \a fg has factors depending on three or more variables or has variables with more than two possible states.
110 */
111 MR( const FactorGraph &fg, const PropertySet &opts );
112
113
114 /// \name General InfAlg interface
115 //@{
116 virtual MR* clone() const { return new MR(*this); }
117 virtual std::string identify() const;
118 virtual Factor belief( const Var &n ) const;
119 virtual Factor belief( const VarSet &/*ns*/ ) const { DAI_THROW(NOT_IMPLEMENTED); return Factor(); }
120 virtual std::vector<Factor> beliefs() const;
121 virtual Real logZ() const { DAI_THROW(NOT_IMPLEMENTED); return 0.0; }
122 virtual void init() {}
123 virtual void init( const VarSet &/*ns*/ ) { DAI_THROW(NOT_IMPLEMENTED); }
124 virtual Real run();
125 virtual Real maxDiff() const { return _maxdiff; }
126 virtual size_t Iterations() const { return _iters; }
127 virtual void setProperties( const PropertySet &opts );
128 virtual PropertySet getProperties() const;
129 virtual std::string printProperties() const;
130 //@}
131
132 private:
133 /// Returns the signum of \a a
134 Real sign(Real a) { return (a >= 0) ? 1.0 : -1.0; }
135
136 /// Initialize N, con, nb, tJ, theta
137 void init(size_t Nin, Real *_w, Real *_th);
138
139 /// Initialize kindex
140 void makekindex();
141
142 /// Initialize cors
143 void init_cor();
144
145 /// Calculate cors using response propagation
146 Real init_cor_resp();
147
148 /// Iterate update equations for cavity fields
149 void solvemcav();
150
151 /// Calculate magnetizations
152 void solveM();
153
154 /// Calculate the product of all tJ[i][_j] for _j in A
155 /** \param i variable index
156 * \param A subset of neighbors of variable \a i
157 */
158 Real _tJ(size_t i, sub_nb A);
159
160 /// Calculate \f$ \Omega^{(i)}_{j,l} \f$ as defined in [\ref MoR05] eqn. (2.15)
161 Real Omega(size_t i, size_t _j, size_t _l);
162
163 /// Calculate \f$ T^{(i)}_A \f$ as defined in [\ref MoR05] eqn. (2.17) with \f$ A = \{l_1,l_2,\dots\} \f$
164 /** \param i variable index
165 * \param A subset of neighbors of variable \a i
166 */
167 Real T(size_t i, sub_nb A);
168
169 /// Calculates \f$ T^{(i)}_j \f$ where \a j is the \a _j 'th neighbor of \a i
170 Real T(size_t i, size_t _j);
171
172 /// Calculates \f$ \Gamma^{(i)}_{j,l_1l_2} \f$ as defined in [\ref MoR05] eqn. (2.16)
173 Real Gamma(size_t i, size_t _j, size_t _l1, size_t _l2);
174
175 /// Calculates \f$ \Gamma^{(i)}_{l_1l_2} \f$ as defined in [\ref MoK07] on page 1141
176 Real Gamma(size_t i, size_t _l1, size_t _l2);
177
178 /// Approximates moments of variables in \a A
179 /** Calculate the moment of variables in \a A from M and cors, neglecting higher order cumulants,
180 * defined as the sum over all partitions of A into subsets of cardinality two at most of the
181 * product of the cumulants (either first order, i.e. M, or second order, i.e. cors) of the
182 * entries of the partitions.
183 *
184 * \param i variable index
185 * \param A subset of neighbors of variable \a i
186 */
187 Real appM(size_t i, sub_nb A);
188
189 /// Calculate sum over all even/odd subsets B of \a A of _tJ(j,B) appM(j,B)
190 /** \param j variable index
191 * \param A subset of neighbors of variable \a j
192 * \param sum_even on return, will contain the sum over all even subsets
193 * \param sum_odd on return, will contain the sum over all odd subsets
194 */
195 void sum_subs(size_t j, sub_nb A, Real *sum_even, Real *sum_odd);
196 };
197
198
199 } // end of namespace dai
200
201
202 #endif