optimization with interdependent variables?

I am using fgoalattain for a multi-objective optimization problem. In this problem, I have some parameter (x) that is dependent on two other variables (y,z). And one of those two variables (y) is dependent on the other (z). So, basically I need to do optimization on two levels for these two variables. How can I do that?

Thanks

[John D'Errico]

Huh?

If x is dependent on the other variables, y and z, then it is NOT something you can independently vary.

Similarly, if y is dependent on z, then it is also not an independent variable.

As such, you have a ONE variable problem. y is a DEPENDENT variable. It is not something you can vary, except by varying z. The same applies to x.

[Abdelrahman Taha]

Sorry if I didn't explain it well. y is a function of z in the sense that the upper limit of y is a function of z.

[Walter Roberson]

Nonlinear constraints on the independent variables y and z. It is not clear whether x is also an independent variable that you would nonlinear constraint

Answer 1

[Bruno Luong]

Optimize with respect to z.

Anything that depend on z, including y and x, such as objectve, constraints, upper bounds..., can be written as function of z.