What will be the latex code for this

Question

Specifically I want the code for this diagram. I am very new to latex…Please help

I would recommend the suggestions here especially Grätzer's More Math into LaTeX. The displayed object can be easily made with an array environment. — Alan Munn, Nov 05 '22 at 19:06

score 2 · Answer 1 · answered Nov 05 '22 at 19:56

I suggest tikz-cd for this diagram. Use arrow type - for the lines, and <-> for the bijection.

The package amsmath (probably already in your document) is needed for \DeclareMathOperator, to get proper spacing and shape of Gal.

\documentclass{article}
\usepackage{amsmath}
\usepackage{tikz-cd}
\DeclareMathOperator{\Gal}{Gal}
\begin{document}
Let $K/F$ be a Galois extension and set $G=\Gal(K/F)$. Denote by $E$ the subfields of $K$ containing $F$ and $H$ the subgroups of $G$. Then there is a bijection:
[
\begin{tikzcd}
K\arrow[d, -] & 1\arrow[d, -]\
E\arrow[d, -]\arrow[r, <->] & H\arrow[d, -]\
F & G
\end{tikzcd}
]
given by the correspondence
\end{document}

score 1 · Answer 2 · answered Nov 05 '22 at 19:56

One solution is given by tikz-cd package like this example.

\documentclass[a4paper,12pt]{article}
\usepackage{tikz-cd}
\begin{document}
\[\begin{tikzcd}[column sep =-1.2]
K                    &                 & 1                    \\
E \arrow[u, no head] & \leftrightarrow & H \arrow[u, no head] \\
F \arrow[u, no head] &                 & G \arrow[u, no head]
\end{tikzcd}\]
\end{document}

score 1 · Answer 3 · answered Nov 06 '22 at 00:09

Without “fancy” packages and avoiding the inconsistency appearing in the image,

\documentclass{article}
\usepackage{amsmath}
\DeclareMathOperator{\Gal}{Gal}
\begin{document}
Let $K/F$ be a Galois extension and set $G=\Gal(K/F)$. 
Denote by $E$ the subfields of $K$ containing $F$ and $H$ 
the subgroups of $G$. Then there is a bijection
[
\begin{array}{ccc}
K && 1 \
\Bigl| && \Bigl| \ \noalign{\vspace{2pt}}
E & \leftrightarrow & H \
\Bigl| && \Bigl| \ \noalign{\vspace{2pt}}
F && G 
\end{array}
]
given by the correspondence
[
\begin{aligned}
E &\rightarrow {\text{elements of $G$ fixing $E$}} \
{\text{the fixed field of $H$}} &\mspace{-1mu}\leftarrow H
\end{aligned}
]
\end{document}

Note the \mspace{-1mu} that's needed to avoid the impression that the arrows are not aligned. Note also the usage of math mode inside \text to have proper italic letters, not the wrong upright ones in the image.

However, since you will be probably needing other diagrams, maybe more complex than the one above, learning the basics of tikz-cd is much better.

What will be the latex code for this

3 Answers3