[tex-k] MacTeX 2013 doesn't leave a space after \dots.

[Reinhard Kotucha]

On 2013-10-06 at 14:36:02 -0400, Abdelmalek Boukhtouchen wrote:

 > I am writing to let you know that MacTex 2013 (TeXlive 2013)
 > doesn't leave a space after \dots between the 3 dots of the
 > ellipsis and the next word on the PDF output, unlike MacTex 2012
 > and the previous versions.

Spaces after a control sequence have always been ignored since TeX
exists.  TeX needs them in order to determine where a control sequence
name ends.  A control sequence name can consist either of letters
(a..z, A..Z) or a single punctuation mark.  The latter case is trivial
because only a single character is involved.  Thus, spaces after it
are preserved.  If a control sequence name consists of letters, the
delimiter can only be a character which is not a letter.  If it's a
space, it's gobbled because otherwise there is no way to omit the
space between the control sequence name and the following text.  Hence
you have to insert the space explicitly if desired.

Examples:

  \TeX book    --- space doesn't appear in the output

  \TeXbook     --- TeX assumes that 'book' is part of the macro name and
                   complains about an undefined control sequence.  

  \TeX{} book  --- the space is preserved because the macro name is
                   delimited by a non-letter character already.

  \TeX3 book   --- same as above (3 is not a letter)

  \TeX\ book   --- as above (note that \<space> is an explicit space).

  \TeX~book    --- as above but no linebreak is allowed between TeX
                   and book

  \TeX\,book   --- small space between TeX and book


 > I have looked on the Internet and it is mentioned nowhere.

It's described in detail in The TeXbook.  It should be mentioned in
any other introductory document about [La]TeX too.  I'm sure you'll
find some information here:

  http://www.tug.org/begin.html

 > Is there something I can do to correct this error or should I
 > uninstall MacTex 2013 and reinstall MacTex 2012 ?

Last question first:  Reverting to an older release doesn't help.  You
would get the same results.

In most cases it's best to put a _small_ space (\,) before and after
\dots.  Investigate yourself, you might have different preferences
within a paragraph or when typesetting math formulas.  There are
also some differences between plain TeX and LaTeX and not all examples
above work well in all environments.

If you have further questions, please ask on the texhax mailing list:

   http://tug.org/mailman/listinfo/texhax

But then please mention whether you are using Plain TeX or LaTeX.
There are subtle differences.

Regards,
  Reinhard

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Reinhard Kotucha                                      Phone: +49-511-3373112
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