When formulating a theorem, which of the following forms would be preferred, and why? Or is there another even better formulation? Are there reasons for or against mixing them in one paper?
Formulation 0: If $x\in X$, then (expression involving $x$).
Formulation 1: Given $x$ in $X$, then (expression involving $x$).
Formulation 2: For all $x$ in $X$ it holds that (expression involving $x$).