When writing an optimization problem, use “minimize” or “maximize” instead of “min” or “max”, and “subject to” instead of “such that” or “s.t.”.

Correct Incorrect
\[\begin{aligned} \operatorname{minimize} \quad & f(x) \\ \operatorname{subject~to} \quad & Ax = b. \end{aligned} \] \[ \begin{aligned} \operatorname{min} \quad & f(x) \\ \operatorname{s.t.} \quad& Ax = b. \end{aligned} \]

The reason that “$\operatorname{min} f(x)$” is objectionable is that the “min” is (by convention) an operator that is short for “minimum”, so the expression “$\operatorname{min} f(x)$” stands for the minimal value of $f$ . Similarly, by convention “s.t.” stands for “such that”, so “$\operatorname{min} f(x)$ s.t. $Ax = b$” should be read as “the minimum value of $f(x)$ such that $Ax = b$. In contrast, “$\operatorname{minimize} f(x)$” is a statement of the goal of the optimization problem with the constraints of the problem given after “subject to”. (As Stephen P. Boyd notes, we could read “s.t.” as an abbreviation of “subject to”, and the same could be said for “min” and “minimize”, but doing so causes use to use the same symbols for different things, which should be avoided.) If space is a concern, you may abbreviate “subject to” as “subj. to” (\operatorname{subj.~to}).

I have shared, here, my definitions of LaTeX macros for \minimize, \maximize, and \subjecto along with example usage.