warm start cp-sat ortools

[Samrat Kadge]

I am carrying out lexicographic optimization in multiple stages.
i.e I optimise a cost and restrict this variable in the next stage to a value less than the best value found in the previous stage.

My "basic" variable is "roster" and all other variables are functionally dependent on the roster, most of them being in the local scope of a constraint/predicate/function.

e.g Number of weekend shifts in the roster.

1. hints are provided using ::warm_start for the roster only.

The current documentation suggests putting ::warm_start in seq_search as well.
Please elaborate if this is useful, or should be avoided.
I do not have a custom search and I am relying on the "default" search from the solver.

2. Subsequent stages of optimization are having difficulty in finding a feasible solution,
which in my opinion is readily available through the "roster" hint from the previous stage.

3. Any performance tips  such as functionally dependent variables should also be hinted, and best practices, is appreciated.

Thanks,
Samrat

[Laurent Perron]

CP-SAT prefers full hints, meaning all variables.

Laurent Perron | Operations Research | lpe...@google.com | (33) 1 42 68 53 00

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[Samrat Kadge]

thanks, will try it out.