How are xtol, ftol, and cvtoldefined and calculated in pymoo?

[oustiottman-dotcom]

Hi everyone,

I'm using pymoo for multi- and many-objective optimization on a mixed-variable problem. I would like to better understand what xtol, ftol, and cvtol really represent, and how they are actually computed.

From what I’ve understood so far:

xtol: relative variation of the decision variables, i.e. the relative change of the solutions in the search space between two consecutive generations.

ftol: relative variation of the objective functions, i.e. the relative change of the objective values between two consecutive generations.

cvtol: variation of constraint violations, i.e. the relative change of the violated constraints between two consecutive generations.

Could anyone confirm if this interpretation is correct, and provide more details on their precise definition and how these values are calculated in practice? I’d like to be fully clear on how to use them properly.

Thanks in advance for your help!