| 1 | <html><head><meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"><title>Chapter 2. |
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| 2 | Basic Model Classes |
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| 3 | </title><meta name="generator" content="DocBook XSL Stylesheets V1.61.2"><link rel="home" href="index.html" title="CBC User Guide"><link rel="up" href="index.html" title="CBC User Guide"><link rel="previous" href="ch01s02.html" title=" |
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| 4 | Prerequisites |
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| 5 | "><link rel="next" href="ch02s02.html" title=" |
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| 6 | First Example |
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| 7 | "></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">Chapter 2. |
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| 8 | Basic Model Classes |
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| 9 | </th></tr><tr><td width="20%" align="left"><a accesskey="p" href="ch01s02.html">Prev</a> </td><th width="60%" align="center"> </th><td width="20%" align="right"> <a accesskey="n" href="ch02s02.html">Next</a></td></tr></table><hr></div><div class="chapter" lang="en"><div class="titlepage"><div><div><h2 class="title"><a name="cbcmodelclass"></a>Chapter 2. |
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| 10 | Basic Model Classes |
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| 11 | </h2></div></div><div></div></div><div class="toc"><p><b>Table of Contents</b></p><dl><dt><a href="ch02.html#hierarchy"> |
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| 12 | Hierarchy and list of classes |
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| 13 | </a></dt><dt><a href="ch02s02.html"> |
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| 14 | First Example |
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| 15 | </a></dt><dt><a href="ch02s03.html"> |
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| 16 | Getting at the Solution (CbcModel methods) |
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| 17 | </a></dt><dt><a href="ch02s04.html">Some Useful Set and Get Methods</a></dt><dt><a href="ch02s05.html"> |
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| 18 | Methods which have a major impact on solution process |
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| 19 | </a></dt></dl></div><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="hierarchy"></a> |
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| 20 | Hierarchy and list of classes |
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| 21 | </h2></div></div><div></div></div><p> |
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| 22 | The class that controls Coin Branch and Cut is CbcModel. This is where most |
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| 23 | of the parameter setting is done. CbcModel uses other classes some of |
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| 24 | which are virtual and may have multiple instances. More details on the more |
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| 25 | useful classes will be given later. |
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| 26 | The absolute minimum number of actions for CbcModel is: |
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| 27 | <tt class="function">CbcModel(OsiSolverInterface & linearSolver)</tt> as constructor, |
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| 28 | and <tt class="function">branchAndBound()</tt> for solving the problem. |
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| 29 | </p><div class="table"><a name="id2896498"></a><p class="title"><b>Table 2.1. Classes used by CbcModel - Most useful</b></p><table summary="Classes used by CbcModel - Most useful" border="0"><colgroup><col><col><col></colgroup><thead><tr><th> |
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| 30 | Class name |
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| 31 | </th><th> |
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| 32 | Description |
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| 33 | </th><th> |
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| 34 | Notes |
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| 35 | </th></tr></thead><tbody><tr><td align="left" valign="top"> |
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| 36 | CbcCompareBase |
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| 37 | </td><td align="left" valign="top"> |
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| 38 | Controls choice of next node on tree |
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| 39 | </td><td align="left" valign="top"> |
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| 40 | Default is CbcCompareDefault, others in CbcCompareActual.hpp include |
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| 41 | CbcCompareDepth and CbcCompareObjective. Very easy for user to |
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| 42 | experiment. |
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| 43 | </td></tr><tr><td align="left" valign="top"> |
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| 44 | CbcCutGenerator |
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| 45 | </td><td align="left" valign="top"> |
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| 46 | Is a CglCutGenerator with data to decide when to use. |
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| 47 | </td><td align="left" valign="top"> |
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| 48 | Need to know how to add generator to CbcModel. |
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| 49 | Not much need to know about details of class. |
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| 50 | </td></tr><tr><td align="left" valign="top"> |
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| 51 | CbcHeuristic |
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| 52 | </td><td align="left" valign="top"> |
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| 53 | Heuristic to try and get valid solutions |
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| 54 | </td><td align="left" valign="top"> |
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| 55 | User can get a lot of value out of coding this. There can be |
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| 56 | as many as you like. |
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| 57 | </td></tr><tr><td align="left" valign="top"> |
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| 58 | CbcObject |
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| 59 | </td><td align="left" valign="top"> |
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| 60 | Definition of what it means for a variable to be satisfied. |
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| 61 | </td><td align="left" valign="top"> |
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| 62 | Virtual - instances include simple integer, simple integer with pseudocosts, |
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| 63 | SOS (type 1 and 2) and lotsizing. (found in CbcBranch..hpp). An object has to |
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| 64 | have a method of generating a branching object which defines an up and down |
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| 65 | branch. |
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| 66 | </td></tr><tr><td align="left" valign="top"> |
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| 67 | OsiSolverInterface |
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| 68 | </td><td align="left" valign="top"> |
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| 69 | Defines the solver being used and the LP model. Is normally |
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| 70 | passed across to CbcModel before branch and cut. |
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| 71 | </td><td align="left" valign="top"> |
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| 72 | Virtual class - the user would instantiate a particular solver e.g. |
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| 73 | OsiClpSolverInterface or OsiXprSolverInterface. |
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| 74 | </td></tr></tbody></table></div><div class="table"><a name="id2897749"></a><p class="title"><b>Table 2.2. Classes used by CbcModel - Least useful</b></p><table summary="Classes used by CbcModel - Least useful" border="0"><colgroup><col><col><col></colgroup><thead><tr><th> |
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| 75 | Class name |
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| 76 | </th><th> |
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| 77 | Description |
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| 78 | </th><th> |
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| 79 | Notes |
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| 80 | </th></tr></thead><tbody><tr><td align="left" valign="top"> |
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| 81 | CbcBranchDecision |
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| 82 | </td><td align="left" valign="top"> |
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| 83 | Part of code for choosing which variable to branch on. Most of |
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| 84 | work is done by definitions in CbcObject |
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| 85 | </td><td align="left" valign="top"> |
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| 86 | Defaults to CbcBranchDefaultDecision |
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| 87 | Not much need to know about. |
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| 88 | </td></tr><tr><td align="left" valign="top"> |
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| 89 | CbcCountRowCut |
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| 90 | </td><td align="left" valign="top"> |
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| 91 | Interface to OsiRowCut but counts use so can gracefully vanish. |
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| 92 | </td><td align="left" valign="top"> |
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| 93 | See OsiRowCut for extra information. |
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| 94 | Not much need to know about. |
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| 95 | </td></tr><tr><td align="left" valign="top"> |
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| 96 | CbcNode |
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| 97 | </td><td align="left" valign="top"> |
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| 98 | Controls choice of variable/entity to branch on |
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| 99 | </td><td align="left" valign="top"> |
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| 100 | Controlled via CbcModel parameters. |
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| 101 | Not much need to know about. |
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| 102 | </td></tr><tr><td align="left" valign="top"> |
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| 103 | CbcNodeInfo |
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| 104 | </td><td align="left" valign="top"> |
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| 105 | Contains data for bounds, basis etc for one node of tree |
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| 106 | </td><td align="left" valign="top"> |
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| 107 | Not much need to know about (header in CbcNode.hpp). |
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| 108 | </td></tr><tr><td align="left" valign="top"> |
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| 109 | CbcTree |
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| 110 | </td><td align="left" valign="top"> |
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| 111 | How tree is stored |
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| 112 | </td><td align="left" valign="top"> |
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| 113 | Can be changed but unlikely. |
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| 114 | Not much need to know about. |
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| 115 | </td></tr><tr><td align="left" valign="top"> |
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| 116 | CoinMessageHandler |
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| 117 | </td><td align="left" valign="top"> |
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| 118 | Deals with message handling |
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| 119 | </td><td align="left" valign="top"> |
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| 120 | User can inherit from to specialize message handling. |
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| 121 | Not much need to know about. |
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| 122 | </td></tr><tr><td align="left" valign="top"> |
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| 123 | CoinWarmStartBasis |
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| 124 | </td><td align="left" valign="top"> |
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| 125 | Representation of a basis to be used by solver |
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| 126 | </td><td align="left" valign="top"> |
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| 127 | Not much need to know about. |
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| 128 | </td></tr></tbody></table></div></div><tt class="function">double getIntegerTolerance()</tt> and |
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| 129 | <tt class="function">setIntegerTolerance(double)</tt>. An integer variable |
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| 130 | is deemed to be at an integral value if it is no further than this tolerance |
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| 131 | away. |
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| 132 | </div><div class="navfooter"><hr><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="ch01s02.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="index.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="ch02s02.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top"> |
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| 133 | Prerequisites |
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| 134 | </td><td width="20%" align="center"><a accesskey="h" href="index.html">Home</a></td><td width="40%" align="right" valign="top"> |
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| 135 | First Example |
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| 136 | </td></tr></table></div></body></html> |
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