1 | // $Id: CbcClique.hpp 1899 2013-04-09 18:12:08Z stefan $ |
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2 | // Copyright (C) 2002, International Business Machines |
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3 | // Corporation and others. All Rights Reserved. |
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4 | // This code is licensed under the terms of the Eclipse Public License (EPL). |
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5 | |
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6 | // Edwin 11/9/2009-- carved out of CbcBranchActual |
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7 | |
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8 | #ifndef CbcClique_H |
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9 | #define CbcClique_H |
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10 | |
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11 | /** \brief Branching object for cliques |
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12 | |
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13 | A clique is defined to be a set of binary variables where fixing any one |
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14 | variable to its `strong' value fixes all other variables. An example is the |
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15 | most common SOS1 construction: a set of binary variables x_j s.t. SUM{j} |
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16 | x_j = 1. Setting any one variable to 1 forces all other variables to 0. |
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17 | (See comments for CbcSOS below.) |
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18 | |
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19 | Other configurations are possible, however: Consider x1-x2+x3 <= 0. |
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20 | Setting x1 (x3) to 1 forces x2 to 1 and x3 (x1) to 0. Setting x2 to 0 |
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21 | forces x1 and x3 to 0. |
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22 | |
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23 | The proper point of view to take when interpreting CbcClique is |
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24 | `generalisation of SOS1 on binary variables.' To get into the proper frame |
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25 | of mind, here's an example. |
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26 | |
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27 | Consider the following sequence, where x_j = (1-y_j): |
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28 | \verbatim |
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29 | x1 + x2 + x3 <= 1 all strong at 1 |
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30 | x1 - y2 + x3 <= 0 y2 strong at 0; x1, x3 strong at 1 |
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31 | -y1 - y2 + x3 <= -1 y1, y2 strong at 0, x3 strong at 1 |
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32 | -y1 - y2 - y3 <= -2 all strong at 0 |
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33 | \endverbatim |
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34 | The first line is a standard SOS1 on binary variables. |
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35 | |
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36 | Variables with +1 coefficients are `SOS-style' and variables with -1 |
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37 | coefficients are `non-SOS-style'. So #numberNonSOSMembers_ simply tells you |
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38 | how many variables have -1 coefficients. The implicit rhs for a clique is |
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39 | 1-numberNonSOSMembers_. |
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40 | */ |
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41 | class CbcClique : public CbcObject { |
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42 | |
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43 | public: |
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44 | |
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45 | /// Default Constructor |
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46 | CbcClique (); |
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47 | |
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48 | /** Useful constructor (which are integer indices) slack can denote a slack |
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49 | in set. If type == NULL then as if 1 |
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50 | */ |
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51 | CbcClique (CbcModel * model, int cliqueType, int numberMembers, |
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52 | const int * which, const char * type, |
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53 | int identifier, int slack = -1); |
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54 | |
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55 | /// Copy constructor |
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56 | CbcClique ( const CbcClique &); |
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57 | |
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58 | /// Clone |
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59 | virtual CbcObject * clone() const; |
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60 | |
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61 | /// Assignment operator |
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62 | CbcClique & operator=( const CbcClique& rhs); |
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63 | |
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64 | /// Destructor |
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65 | virtual ~CbcClique (); |
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66 | |
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67 | /// Infeasibility - large is 0.5 |
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68 | virtual double infeasibility(const OsiBranchingInformation * info, |
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69 | int &preferredWay) const; |
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70 | |
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71 | using CbcObject::feasibleRegion ; |
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72 | /// This looks at solution and sets bounds to contain solution |
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73 | virtual void feasibleRegion(); |
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74 | |
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75 | /// Creates a branching object |
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76 | virtual CbcBranchingObject * createCbcBranch(OsiSolverInterface * solver, const OsiBranchingInformation * info, int way) ; |
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77 | /// Number of members |
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78 | inline int numberMembers() const { |
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79 | return numberMembers_; |
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80 | } |
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81 | /** \brief Number of variables with -1 coefficient |
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82 | |
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83 | Number of non-SOS members, i.e., fixing to zero is strong. |
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84 | See comments at head of class, and comments for #type_. |
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85 | */ |
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86 | inline int numberNonSOSMembers() const { |
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87 | return numberNonSOSMembers_; |
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88 | } |
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89 | |
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90 | /// Members (indices in range 0 ... numberIntegers_-1) |
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91 | inline const int * members() const { |
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92 | return members_; |
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93 | } |
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94 | |
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95 | /*! \brief Type of each member, i.e., which way is strong. |
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96 | |
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97 | This also specifies whether a variable has a +1 or -1 coefficient. |
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98 | - 0 => -1 coefficient, 0 is strong value |
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99 | - 1 => +1 coefficient, 1 is strong value |
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100 | If unspecified, all coefficients are assumed to be positive. |
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101 | |
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102 | Indexed as 0 .. numberMembers_-1 |
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103 | */ |
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104 | inline char type(int index) const { |
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105 | if (type_) return type_[index]; |
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106 | else return 1; |
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107 | } |
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108 | |
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109 | /// Clique type: 0 is <=, 1 is == |
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110 | inline int cliqueType() const { |
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111 | return cliqueType_; |
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112 | } |
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113 | /// Redoes data when sequence numbers change |
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114 | virtual void redoSequenceEtc(CbcModel * model, int numberColumns, const int * originalColumns); |
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115 | |
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116 | protected: |
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117 | /// data |
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118 | /// Number of members |
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119 | int numberMembers_; |
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120 | |
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121 | /// Number of Non SOS members i.e. fixing to zero is strong |
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122 | int numberNonSOSMembers_; |
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123 | |
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124 | /// Members (indices in range 0 ... numberIntegers_-1) |
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125 | int * members_; |
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126 | |
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127 | /** \brief Strong value for each member. |
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128 | |
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129 | This also specifies whether a variable has a +1 or -1 coefficient. |
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130 | - 0 => -1 coefficient, 0 is strong value |
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131 | - 1 => +1 coefficient, 1 is strong value |
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132 | If unspecified, all coefficients are assumed to be positive. |
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133 | |
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134 | Indexed as 0 .. numberMembers_-1 |
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135 | */ |
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136 | char * type_; |
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137 | |
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138 | /** \brief Clique type |
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139 | |
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140 | 0 defines a <= relation, 1 an equality. The assumed value of the rhs is |
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141 | numberNonSOSMembers_+1. (See comments for the class.) |
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142 | */ |
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143 | int cliqueType_; |
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144 | |
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145 | /** \brief Slack variable for the clique |
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146 | |
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147 | Identifies the slack variable for the clique (typically added to convert |
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148 | a <= relation to an equality). Value is sequence number within clique |
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149 | menbers. |
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150 | */ |
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151 | int slack_; |
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152 | }; |
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153 | |
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154 | /** Branching object for unordered cliques |
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155 | |
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156 | Intended for cliques which are long enough to make it worthwhile |
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157 | but <= 64 members. There will also be ones for long cliques. |
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158 | |
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159 | Variable_ is the clique id number (redundant, as the object also holds a |
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160 | pointer to the clique. |
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161 | */ |
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162 | class CbcCliqueBranchingObject : public CbcBranchingObject { |
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163 | |
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164 | public: |
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165 | |
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166 | // Default Constructor |
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167 | CbcCliqueBranchingObject (); |
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168 | |
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169 | // Useful constructor |
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170 | CbcCliqueBranchingObject (CbcModel * model, const CbcClique * clique, |
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171 | int way, |
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172 | int numberOnDownSide, const int * down, |
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173 | int numberOnUpSide, const int * up); |
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174 | |
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175 | // Copy constructor |
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176 | CbcCliqueBranchingObject ( const CbcCliqueBranchingObject &); |
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177 | |
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178 | // Assignment operator |
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179 | CbcCliqueBranchingObject & operator=( const CbcCliqueBranchingObject& rhs); |
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180 | |
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181 | /// Clone |
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182 | virtual CbcBranchingObject * clone() const; |
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183 | |
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184 | // Destructor |
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185 | virtual ~CbcCliqueBranchingObject (); |
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186 | |
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187 | using CbcBranchingObject::branch ; |
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188 | /// Does next branch and updates state |
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189 | virtual double branch(); |
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190 | |
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191 | using CbcBranchingObject::print ; |
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192 | /** \brief Print something about branch - only if log level high |
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193 | */ |
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194 | virtual void print(); |
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195 | |
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196 | /** Return the type (an integer identifier) of \c this */ |
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197 | virtual CbcBranchObjType type() const { |
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198 | return CliqueBranchObj; |
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199 | } |
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200 | |
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201 | /** Compare the original object of \c this with the original object of \c |
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202 | brObj. Assumes that there is an ordering of the original objects. |
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203 | This method should be invoked only if \c this and brObj are of the same |
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204 | type. |
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205 | Return negative/0/positive depending on whether \c this is |
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206 | smaller/same/larger than the argument. |
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207 | */ |
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208 | virtual int compareOriginalObject(const CbcBranchingObject* brObj) const; |
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209 | |
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210 | /** Compare the \c this with \c brObj. \c this and \c brObj must be of the |
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211 | same type and must have the same original object, but they may have |
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212 | different feasible regions. |
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213 | Return the appropriate CbcRangeCompare value (first argument being the |
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214 | sub/superset if that's the case). In case of overlap (and if \c |
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215 | replaceIfOverlap is true) replace the current branching object with one |
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216 | whose feasible region is the overlap. |
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217 | */ |
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218 | virtual CbcRangeCompare compareBranchingObject |
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219 | (const CbcBranchingObject* brObj, const bool replaceIfOverlap = false); |
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220 | |
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221 | private: |
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222 | /// data |
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223 | const CbcClique * clique_; |
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224 | /// downMask - bit set to fix to weak bounds, not set to leave unfixed |
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225 | unsigned int downMask_[2]; |
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226 | /// upMask - bit set to fix to weak bounds, not set to leave unfixed |
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227 | unsigned int upMask_[2]; |
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228 | }; |
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229 | |
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230 | /** Unordered Clique Branching Object class. |
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231 | These are for cliques which are > 64 members |
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232 | Variable is number of clique. |
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233 | */ |
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234 | class CbcLongCliqueBranchingObject : public CbcBranchingObject { |
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235 | |
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236 | public: |
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237 | |
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238 | // Default Constructor |
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239 | CbcLongCliqueBranchingObject (); |
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240 | |
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241 | // Useful constructor |
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242 | CbcLongCliqueBranchingObject (CbcModel * model, const CbcClique * clique, |
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243 | int way, |
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244 | int numberOnDownSide, const int * down, |
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245 | int numberOnUpSide, const int * up); |
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246 | |
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247 | // Copy constructor |
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248 | CbcLongCliqueBranchingObject ( const CbcLongCliqueBranchingObject &); |
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249 | |
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250 | // Assignment operator |
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251 | CbcLongCliqueBranchingObject & operator=( const CbcLongCliqueBranchingObject& rhs); |
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252 | |
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253 | /// Clone |
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254 | virtual CbcBranchingObject * clone() const; |
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255 | |
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256 | // Destructor |
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257 | virtual ~CbcLongCliqueBranchingObject (); |
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258 | |
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259 | using CbcBranchingObject::branch ; |
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260 | /// Does next branch and updates state |
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261 | virtual double branch(); |
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262 | |
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263 | using CbcBranchingObject::print ; |
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264 | /** \brief Print something about branch - only if log level high |
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265 | */ |
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266 | virtual void print(); |
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267 | |
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268 | /** Return the type (an integer identifier) of \c this */ |
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269 | virtual CbcBranchObjType type() const { |
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270 | return LongCliqueBranchObj; |
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271 | } |
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272 | |
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273 | /** Compare the original object of \c this with the original object of \c |
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274 | brObj. Assumes that there is an ordering of the original objects. |
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275 | This method should be invoked only if \c this and brObj are of the same |
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276 | type. |
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277 | Return negative/0/positive depending on whether \c this is |
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278 | smaller/same/larger than the argument. |
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279 | */ |
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280 | virtual int compareOriginalObject(const CbcBranchingObject* brObj) const; |
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281 | |
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282 | /** Compare the \c this with \c brObj. \c this and \c brObj must be os the |
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283 | same type and must have the same original object, but they may have |
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284 | different feasible regions. |
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285 | Return the appropriate CbcRangeCompare value (first argument being the |
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286 | sub/superset if that's the case). In case of overlap (and if \c |
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287 | replaceIfOverlap is true) replace the current branching object with one |
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288 | whose feasible region is the overlap. |
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289 | */ |
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290 | virtual CbcRangeCompare compareBranchingObject |
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291 | (const CbcBranchingObject* brObj, const bool replaceIfOverlap = false); |
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292 | |
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293 | private: |
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294 | /// data |
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295 | const CbcClique * clique_; |
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296 | /// downMask - bit set to fix to weak bounds, not set to leave unfixed |
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297 | unsigned int * downMask_; |
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298 | /// upMask - bit set to fix to weak bounds, not set to leave unfixed |
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299 | unsigned int * upMask_; |
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300 | }; |
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301 | |
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302 | #endif |
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303 | |
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