0

I'm trying to reproduce this text in Latex

enter image description here

On the left you see what I could achieve by now, with the following LaTeX code:

\polyring{\mathbb R}{x}_{/\ideal{x^2+1}}\mathrel{\mathop{\rightleftarrows}^{\mathrm{\alpha}}_{\mathrm{\beta}}} \mathbb C

Where \polyring and \ideal are defined as follows:

\newcommand{\polyring}[2]{\ensuremath{#1\big[#2\big]}}
\newcommand{\ideal}[1]{\ensuremath{\langle #1\rangle}}

Instead on the right you see the result I'd like to achieve. I couldn't find anything that would satisfy my needs. TIA.

hbghlyj
  • 201
  • 1
  • 8
Baffo rasta
  • 281

1 Answers1

1

Such a double arrow doesn't exist in amsmath, but the extpfeil package provides one under the name \xtofrom[under]{above}.

I took the liberty to redefine your \ideal command with \DeclarePairedDelimiter command from mathtools. Last the mathrm version of greek letters doesn't exist (unless you use a font such as fourier which defines them), but you have the upgreek package.

\documentclass{article}
\usepackage{mathtools, amssymb}
\usepackage{extpfeil, upgreek}
\DeclarePairedDelimiter{\ideal}\langle \rangle
\newcommand{\polyring}[2]{\ensuremath{#1\big[#2\big]}}

\begin{document}


\[ \polyring{\mathbb R}{x}_{/\ideal{x^2+1}}\xtofrom[\upbeta] {\enspace \upalpha\enspace }\mathbb C \]%




\end{document}

enter image description here

Edit:

Another possibility, with tikz-cd:

    \[ \begin{tikzcd}[column sep=large]
     \polyring{\mathbb R}{x}_{/\ideal{x^2+1}}\rar["\upalpha", shift left] & \mathbb C \lar["\upbeta", shift left]
    \end{tikzcd} \]

enter image description here

Sebastiano
  • 54,118
Bernard
  • 271,350
  • Thank you for your answer! It's almost what I needed, but I'd like the two arrows to be more spaced vertically, since when I print it to an A4 size PDF it looks like this: https://imgur.com/a/GwaSA4s and you kind of not see the symbol very clearly. – Baffo rasta Apr 17 '21 at 16:57
  • I agree with you. It has the advantage of a simple syntax. Another solution would be to you use tikz-cd which gives the possibility to control the spacing, but the syntax is a bit more complex, but if you don't have to insert it in a wider set of equations, it's quite doable. B. t.w., where did you take this notation for quotient rings? It is not standard, as far as I know. – Bernard Apr 17 '21 at 18:54
  • It is the notation our teacher used during the lectures. I'm just trying to make good and clean notes for me to study better without going crazy to find an information I need. – Baffo rasta Apr 17 '21 at 18:55
  • @Bafforasta: Please take a look at my edit, which uses the solution with tikz-cd. – Bernard Apr 17 '21 at 19:27
  • Thank you, that looks great now! – Baffo rasta Apr 17 '21 at 20:28
  • @Bafforasta: Thank you for your kind appreciation. A last suggestion: I thought maybe, what your teacher meant for the notation of a quotient structure is what one obtains with the faktor package. You should take a look at its (short) documentation. – Bernard Apr 17 '21 at 21:15
  • Thank you for all your really useful suggestions, I'll definitely look into it. – Baffo rasta Apr 17 '21 at 21:22