[Tex/LaTex] Spacing around a comma to separates conditions (in math mode)

math-modepunctuation

Let say I have a set

\{ x \in A : first condition , second condition , third condition \},

or as a more explicit example

\{ x \in A : x > 0 , x^2 \in B , x^3 \notin C \}.

I find that the spacing around the commas are too small, and sometime it makes it hard to identify the different conditions. What would be a good practice to have nice spacing there?

I thought of \ , \. But I really does not like it, since the code is messy afterwards. An other solution I thought of is \mathbin{,} or \mathrel{,}.
Does anyone has better suggestion or motivations for choosing one of these solutions over the others.

Best Answer

Related to something I wrote recently, I would use ,\ in math mode, and just “text mode” when text is involved. I put “” because by text mode I don't mean \text.

\newcommand*\mathwords{\textnormal}
$\{ x \in A : \mathwords{first condition, second condition, third condition} \}$
$\{ x \in A : x > 0 ,\ x^2 \in B ,\ x^3 \notin C \}$

Something should be done so that TeX would break between lines and hyphenate the words in \mathwords, ideally. But here it's just an example.

Related Solutions

[Tex/LaTex] Ugly spacing around f in math mode

For a detailed answer why this is happening you can read this answer of mine (shameless plug indeed): In short, the italic correction of the f has a great part in this. But the italic correction only explains the spacing after the f, not before. For this you have to look at the bounding boxes of the letters:

The first f is a text italic letter in its bounding box, the second one is math italic (in its bounding box together with its italic correction). As you can see, the text letter protrudes a bit to the left (and a lot to the right); the math letter has a tiny bit of white space in the left (and also in the right, because of the italic correction). For a bit more about the bounding boxes see this question of mine (another shameless plug :-)).

I first noticed the problem when typing $Vf$ , which doesn't yield a nice output. My resort is using $V\hspace{-0.1em}f$ instead (in a macro, of course), which I like much better. You could even use $V\!f$ , but this I find too narrow. Compare these three:

I would not encourage you to follow Caramdir's (now removed) suggestion to use $\mathit{Vf}$ since this uses a different font (text italic, not math italic). You can see quite clearly that the V is narrower (in other words, the angle at the bottom of the V is more acute):

If you use a different math font (like Euler), then the difference is even more noticeable.

(For a case where \textit could be a good solution, see this answer of TH.)

[Tex/LaTex] Quotation marks around operator in math mode

Declare \mlq and so on as \mathrel, because TeX doesn't add space between consecutive relation symbols:

\documentclass[varwidth,border=3pt]{standalone}
\usepackage{amsmath}
\DeclareMathSymbol{\mlq}{\mathrel}{operators}{``}
\DeclareMathSymbol{\mrq}{\mathrel}{operators}{`'}
\DeclareMathSymbol{\mlqq}{\mathrel}{operators}{"5C}
\DeclareMathSymbol{\mrqq}{\mathrel}{operators}{`"}

\begin{document}

$Op \mapsto Op \mlq\rightarrow\mrq Op$

$Op \mapsto Op \mlqq\rightarrow\mrqq Op$

Quotation marks close to arrow: ``$\rightarrow$''
\end{document}

enter image description here

If you need quotes around other symbols, you can follow a different path; declare the quotes as ordinary symbols (with \mathord) and define

\newcommand{\qto}{\mathrel{\mlq}\to\mathrel{\mrq}}
\newcommand{\qqto}{\mathrel{\mlqq}\to\mathrel{\mrqq}}

so you can have something like

$\mlq A\mrq \qqto \mlqq B\mrqq$

without worrying about spacings.

Best Answer

Related Solutions

[Tex/LaTex] Ugly spacing around f in math mode

[Tex/LaTex] Quotation marks around operator in math mode

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