Mingled math and text in math mode

Question

I frequently encounter the situation of wanting to, say, write a set where the set-membership condition involves some text. If I wanted to describe, say, the set of all even integers this way, then would it be better to write

\{x \in \mathbb Z : \text{$x$ is even}\}

or

\{x \in \mathbb Z : x\text{ is even}\}

? Of course there are obvious quibbles (maybe you like \mathbb{Z} rather than \mathbb Z; maybe you like some other delimiter than :, or some manual space around it), but I'm asking only which way is preferable for writing intermingled text and math in math mode—and, if possible, a reason why other than personal preference.

(I was convinced long ago to use the former by someone who argued that it's semantically more sensible, but I don't know if it's the best practice, or, if it is, whether there's any TeXnical reason for it.)

I vote for the second one, see if this post: https://tex.stackexchange.com/questions/3415/what-is-the-correct-way-of-embedding-text-into-math-mode may help you. — CarLaTeX, Dec 30 '19 at 06:36
@CarLaTeX, thanks! That seems to be more about mbox vs. mathrm than the issue raised here; but this issue did come up, and anon voted for the first. — LSpice, Dec 30 '19 at 07:00
I'm not an expert, I can't give you a TeX reason for my preference, let's see if some TeXnician replies :) — CarLaTeX, Dec 30 '19 at 07:08
I would prefer the first way. Only reason: it’s more readable. — fractal, Dec 30 '19 at 07:40
@Fractal, more readable as source or as compiled document, or both? — LSpice, Dec 30 '19 at 07:58
\{ ...\} ? ... I would use simply $x \in \mathbb Z : x$ is even — Fran, Dec 30 '19 at 07:59
@LSpice Please only @ me without the link, otherwise I am not notified. Answer: the source is more readable. The document? It doesn't change at all. — fractal, Dec 30 '19 at 08:11
@Fran Using \{ \} is the standard notation in some countries including mine. — fractal, Dec 30 '19 at 08:12

score 2 · Answer 1 · answered Sep 26 '20 at 19:16

\{x \in \mathbb Z : \text{$x$ is even}\}

is semantically correct and preferable.

The output of both options will be identical in terms of spacing, but semantically, the x in “x is even” belongs to the phrase which is text mode and not to the surrounding context.

score 0 · Answer 2 · edited Jun 10 '20 at 12:32

0

Note Do not use this method for your actual work or in your professional capacity. It is a mere jeu d'esprit. This is not recommended for actual maths, which is 99% layout (such as glyph shapes, spacings and proportions and so on, to convey meaning in a standardized way), but is meant only to illustrate that all unicode glyphs are just that, glyphs, and so are "text-able" (as far as that can take anyone). There is a (natural) tendency to consider the (996) mathematical alphanumeric symbols as just a text glyph with formatting applied (e.g. bold, italic), or originating from a different font file/style altogether (e.g., sans, fraktur, script), but, in Unicode, all these are completely different glyphs (in the same font), not just the same text x codepoint in fancy dress (from potentially a mixture of different fonts).

Just to celebrate end-of-year, without delimiters ...

If I type directly in unicode:

 ∈ ℤ :  is even

(and the font has text Latin in it as well, like XITS Math does), then I get:

MWE

\documentclass[border=6pt]{standalone}
\usepackage{fontspec}
\setmainfont{XITS Math}
%\usepackage{unicode-math}
%\setmathfont{XITS Math}
\begin{document}
%\[x \in \mathbb Z : \text{$x$ is even}\]
∈ ℤ :  is even
\end{document}

... so the question is moot, perhaps. :)

edited Jun 10 '20 at 12:32

Community

1

answered Dec 30 '19 at 10:56

Cicada

10,129

5

Sorry, but I don't recommend this way. The , ∈ and ℤ are treated as in text mode, so unexpected things may happen. Moreover, the spacing is not the "standard" consistent math spacing, but only a normal text-mode space. – fractal Dec 30 '19 at 10:59
1

I agree with @Fractal, this is not the way to go, sorry but -1 – CarLaTeX Dec 30 '19 at 11:01
@CarLaTeX I don't think a downvote is necessary. From his wording, it is quite clear that this answer is not meant to be serious. It is kind of "just for fun". – fractal Dec 30 '19 at 11:03
@Fractal I like fun posts but not if they give wrong information. – CarLaTeX Dec 30 '19 at 11:10
@CarLaTeX Ah, I remember that sad episode. – fractal Dec 30 '19 at 11:11
I'll add a rider, to make it clearer. – Cicada Dec 31 '19 at 09:59
I've left my downvote due to your edit, thanks! – CarLaTeX Dec 31 '19 at 15:46

Davislor · Answer 3 · 2020-09-26T16:33:51.020

I’d say the best practice is to write

x \textnormal{ is even}

As for x \textnormal{...} versus \textnormal{$x$ ...}, the former is simpler and the latter can easily lead to mismatched $ signs. You could at least alleviate that with \textnormal{$x$ is even}, but that takes even more characters.

Unlike \text, this resets all formatting. If you’ve changed the formatting of the surrounding text—such as an italicized theorem statement, or a bold header, that would bleed through into math mode if you use \text. (Which might be what you want in some cases.)

Mingled math and text in math mode

3 Answers3