How do I ensure a single character for \ldots

Question

How do I ensure that \ldots comes out in the PDF as a single character?

I'm formatting a document for a publisher, who has given this condition in its formatting rules, but I do not know how I can do this in LaTeX.

I'm using MiKTeX 2.9

EDIT: Yes the question could be phrased as: is it possible for \ldots to produce a single "triple point glyph" rather than 3 separate dots (like "..."), since that's what it currently does.

Following the suggestion of kahen, I tried with XeLaTeX and the ellipsis character "…" as well as the \ldots command. Both worked and looked the same.

Answer 1

The command \ldots, which works both in text mode and in math mode, will create a single glyph in xelatex and lualatex, assuming you're using a font that knows how to set character U+2026, "Horizontal Ellipsis."

In an earlier version of this answer, I mistakenly referred to what's created in pdflatex by the \ldots command as a "single glyph". In fact, it's composed of three separate dots, concatenated by non-breaking whitespace. Thus, while it's not a single glyph in the narrow, technical sense, it behaves like one for typesetting purposes. For instance, it won't ever get broken up across two lines.

Answer 2

You could use the dots family from the MnSymbol package; in the following example I used \hdots to define a new command \Ldots to produce the same result as \hdots, but using lowered instead of centered dots (I used \mathop in my definition to give the symbol the spacing corresponding to a standard operator, but you could replace it with \mathord to get the same spacing as \hdots):

\documentclass{article}
\usepackage{MnSymbol}

\newcommand\Ldots{\mathop{\lower.5ex\hbox{$\hdots$}}}

\begin{document}

\[ a\hdots b \]

\[ a\Ldots b \]

\end{document}

This remark is on page 64 of the The Comprehensive LaTeX Symbol List :

Also, unlike most of the other dot symbols in this document, MnSymbol’s dots are defined as single characters instead of as composites of multiple single-dot characters.