[Tex/LaTex] Math spacing when using quantifiers

equationsmath-modespacing

I'm often writing equations with quantifiers like these:

\begin{equation*}
x_i \quad \forall i = 1, \dotsc, n
\end{equation*}


I've read this answer, but I'm not sure if my case is an example for a situation where one uses EM quad.

So my first question is, would you put a \quad space at that position?

The second question is, would you separate the first part from the quantifier with a comma like:

\begin{equation*}
x_i \quad , \forall i = 1, \dotsc, n
\end{equation*}


Don't put a space before the comma, Also I would not use \forall with an informal iterator displayed as dots.

Assuming x_i is some boolean valued expression indexed by i then either

\begin{equation*}
x_i \quad \text{for all $i=1,\dots,n$}
\end{equation*}


or more formally

\begin{equation*}
\forall i \in \{1,\dots,n\}\mathbin{.}x_i
\end{equation*}