Briefly, the algorithm that populates the solution pool works in two phases.

In the first phase, it solves the model to optimality (or some stopping criterion set by the user) while it sets up a search tree for the second phase.

In the second phase, it generates multiple solutions by using the information computed and stored in the first phase and by continuing to explore the tree.

The amount of preparation in the first phase and the intensity of exploration in the second phase are controlled by the pool intensity parameter:

After a model has been read (or created), the first call to populate will carry out both the first and second phase. In the general case, subsequent calls to populate will re-use stored information and proceed with the continuation of the second phase. The first phase will be re-computed if:

The details of the algorithm that populates the solution pool are published in the paper titled "Generating Multiple Solutions for Mixed Integer Programming Problems," by Emilie Danna, Mary Fenelon, Zhonghao Gu, and Roland Wunderling, in the Proceedings of the Twelfth Conference on Integer Programming and Combinatorial Optimization IPCO 2007, pages 280 - 294.