ILOG CPLEX 11.0 User's Manual > Discrete Optimization > Solution Pool: Generating and Keeping Multiple Solutions > Enumerating All Solutions

Enumerating All Solutions

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With the solution pool, you can collect all solutions to a MIP model. To do so, set the solution pool intensity parameter to its highest value, 4, and call populate.

You can also enumerate all solutions that are valid for a specific criterion. For example, if you want to enumerate all alternative optimal solutions, do the following:

  1. Set the pool absolute gap parameter (SolnPoolAGap, CPX_PARAM_SOLNPOOLAGAP) to 0.0 (zero).
  2. Set the pool intensity parameter to 4 (SolnPoolIntensity, CPX_PARAM_SOLNPOOLINTENSITY).
  3. Set the populate limit parameter (PopulateLim, CPX_PARAM_POPULATELIM) to a value sufficiently large for your model; for example, 2 100 000 000.
  4. Call populate.

Beware, however, that, even for small models, the number of possible solutions is likely to be huge. Consequently, enumerating all of them will take time and consume a large quantity of memory.

In addition, when you attempt to enumerate all solutions, some restrictions apply, as explained in the following sections.

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