How to store multiple solutions with the same objVal in my SolPool?

I have set the solution params according to online tutorial as follow.

model_handler.build_sp(data)
model_handler.SP.Params.PoolSolutions = 30
model_handler.SP.Params.PoolSearchMode = 2
model_handler.SP.optimize()

However, the SolPool is still 1, seen as follow:

model_handler.SP.SolCount
Python 3.9.6 (default, Dec 7 2023, 05:42:47)
Type 'copyright', 'credits' or 'license' for more information
IPython 8.6.0 -- An enhanced Interactive Python. Type '?' for help.
PyDev console: using IPython 8.6.0
Out[1]: 1

When I add a constraint to avoid the same solution to the model and solved it, another solution comes with the same objVal. This told the model has other good solution. I want k of them stored in the solution pool.

Ronald van der Velden

Gurobi Staff

January 16, 2024 08:04 Edited

Do the solutions you found, only differ in the value of continuous variables or also in binary/integer variables? See this article for some limitations, e.g. how we consider whether two solutions are equal or not. Let me know if that helps!

zichun ji

January 16, 2024 08:02

THANKS. The variables are all continuous type, and comes out to be 0 or 1 in the solution. I can't find the article, is there any link?

January 16, 2024 08:04

Apologies, something went wrong there - I just added the link above.

January 16, 2024 08:21

MANY THANKS! Turning the type to binary works.

How to store multiple solutions with the same objVal in my SolPool?

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