Save solver state

[rybickibartek]

What language and solver does this apply to?
Python, CP-SAT

Describe the problem you are trying to solve.
I would like to store solver state between sessions / executions.

I am running CP-SAT on an optimization model. I stop it at some point and add some new constraints

• set of variables is the same
• some variables are fixed with values [these are only constraints added]
• best found solution is feasible
• all variables have hint [last found solution]

I would like a solver to start from 'posiiton' in which I stopped it - to do not check solutions already seen in previous session(s) / execution(s).

Is it possible to be done? Or maybe it is already implemented?

[lperron]

The solve() itself is stateless.
You can store the last solution, and restart from it using hints in the model.

See https://github.com/google/or-tools/blob/stable/ortools/sat/docs/model.md#solution-hinting

[rybickibartek]

This is exactly what I am doing. But does it prevents solver from checking already visited partial solutions which leads either infeasible solutions or solutions with are worst then best already observed solution?

[pramitbiswas]

@lperron Can you please update the link, or provide relevant information?

[lperron]

Done

[lperron]

No, it does not. Still, it is the best you can do actually. Laurent Perron | Operations Research | [email protected] | (33) 1 42 68 53 00 Le lun. 8 mars 2021 à 16:17, rybickibartek <[email protected]> a écrit :

…

This is exactly what I am doing. But does it prevents solver from checking already visited partial solutions which leads to either infeasible solutions or solutions with are worst then best already observed solution? — You are receiving this because you modified the open/close state. Reply to this email directly, view it on GitHub <#2427 (reply in thread)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/ACUPL3PVESTPRFPSOOOLXETTCTS7JANCNFSM4YZSHYHA> .

[rybickibartek]

Ok great, thanks for help!