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KEEPMIPSOL

Description

Branch and Bound: The number of integer solutions to store. During a global search, any number of integer solutions may be found, which may or may not represent optimal solutions. See XPRSglobal (GLOBAL). Goal Programming: The number of partial solutions to store in the pre‑emptive goal programming. Pre‑emptive goal programming solves a sequence of problems giving a sequence of partial solutions. See XPRSgoal (GOAL). The stored solutions can only be accessed in a limited way - see the notes below. An alternative method of storing multiple integer solutions from the Optimizer library (or Mosel) is to use an integer solution callback function to retrieve and store them - see XPRSsetcbintsol for details.

Type

Integer

Values

1	store the best/final solution only.
n=2-11	store the n best/most recent solutions.

Default value

Notes

Multiple solutions are kept by storing them on separate binary solution files. The best/final solution is stored on the default solution file, probname.sol, as usual. The next best solution (if found) is stored on a solution file named probname.so0, the next best on probname.so1, and so on up to probname.so9, or until there are no further solutions. The only function able to access the multiple solution files is XPRSwritesol (WRITESOL) - refer to its "e" flag. It is also possible to use other functions that access the solution from the solution file by renaming a particular stored solution file, e.g., probname.so3, to the default solution file probname.sol before using the function. A list of functions that may be used to access the solution from the solution file may be found under the SOLUTIONFILE control.

Affects routines

XPRSglobal (GLOBAL), XPRSgoal (GOAL).