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We all know that expressions in mathematical optimization models can't contain "black boxes" around a decision variable since everything has to be written using mathematical expressions. For example, "yes/no" decisions can't be written as "if this then that" expressions in a model, but can be written using big-$M$ constraints with a binary variable.

What is the recommended way of writing a model that must compute the value of a cumulative distribution function from a decision variable?

For example, let's suppose we have a model with the following constraint:

$$\Phi_X(x)\le b$$

where $\Phi_X(x)$ is the cumulative distribution function of the standard Normal random variable $X\sim N(\mu = 0,\sigma =1)$, $x$ is a decision variable, and $b$ is a parameter of the model.

Is there any way of converting this kind of constraint into a valid mathematical formulation? What is the approach suggested by experts? Does that kind of constraint absolutely require the use of special tools that can't be found in regular optimization solvers?

SecretAgentMan
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V. Brunelle
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1 Answers1

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For strictly increasing CDFs, you can invert: $$x \le \Phi^{-1}(b)$$

RobPratt
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