I'm wondering what are the typographic standards for the placement of commas/dots in the following (and similar) case:\ enter image description here

The first option looks nicer, the second seems to be more logically consistent.

  • In the TeXbook Knuth uses something like \begin{equation} d=\begin{cases} (l+b)^2+p^2,&\text{if $0\le p<10000$};\\ (l+b)^2-p^2,&\text{if $-10000<p<0$};\\ (l+b)^2,&\text{if $p\le-10000$}.\end{cases} \end{equation}. See also tex.stackexchange.com/q/499/35864
    – moewe
    Dec 21, 2019 at 20:31
  • 2
    You may also be interested in what the AMS style guide has to say on the issue (ams.org/arc/styleguide/AMSstyleguide.pdf, §13.11)
    – moewe
    Dec 21, 2019 at 20:36
  • 3
    I don't find the second option logically consistent, besides being typographically abominable.
    – egreg
    Dec 21, 2019 at 21:15
  • My goto rule for this is to use the same punctuation that you'd use if this wasn't in display mode, aka the first one.
    – daleif
    Dec 21, 2019 at 21:22

1 Answer 1


As a reference, page 109 of the AMS style guide (http://www.ams.org/arc/styleguide/AMSstyleguide.pdf) suggests that the first is preferred (at least by the AMS).

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