# itemize inside an equation

I am trying to use itemize inside an equation, but I am getting a bunch of errors

\documentclass[12pt,a4paper]{article}
\usepackage[utf8]{inputenc}
\usepackage{amsmath}
\usepackage{amsfonts}
\usepackage{amssymb}
\begin{document}
$$\begin{itemize} \item V_{p}=\Biggl\{F\in\Phi\hspace{2mm}\Bigg|\begin{cases} p^2\nmid \text{disc}(F)\hspace{1mm} \text{if}\hspace{1mm} p\neq 2 \item\text{disc}(F)\equiv 1\pmod 4 \vee \text{disc}(F)\equiv 8\vee 12 \pmod{16} \hspace{1mm}\text{if} \hspace{1mm}p=2\Biggr\} \end{itemize}$$
\end{document}


so I tried with begin cases instead but I am not really satisfied with how it looks

\documentclass[12pt,a4paper]{article}
\usepackage[utf8]{inputenc}
\usepackage{amsmath}
\usepackage{amsfonts}
\usepackage{amssymb}
\begin{document}
$$V_{p}=\Biggl\{F\in\Phi\hspace{2mm}\Bigg|\begin{cases} p^2\nmid \text{disc}(F)\hspace{1mm} \text{if}\hspace{1mm} p\neq 2\\\text{disc}(F)\equiv 1\pmod 4 \vee \text{disc}(F)\equiv 8\vee 12 \pmod{16} \hspace{1mm}\text{if} \hspace{1mm}p=2\Biggr\} \end{cases}$$
\end{document}


and the output

I would like to get something similar but without being forced to use ''begin cases'', I thought itemize would look better after the vertical line. Does anyone have an idea how to make this equation to look prettier?

• Instead of cases you could use gathered. And instead of the manual \hspace, it would be better if you just left a space in the \text{} macro which is where you want the space anyway. Mar 19, 2014 at 18:14
• @user124471 you could also use aligned within the equation environment. Mar 19, 2014 at 19:29

A solution with small bullets, and your code simplified, using the nccmath , relsize and braket packages. I patched the definition of the \Set command thanks to David Carlisle to improve the spacing of the braces. Note that "discr" is actually a math operator, and I declare it as such, in order to have better horizontal spacings.

    \documentclass[11pt, a4paper]{article}
\usepackage[utf8]{inputenc}
\usepackage[T1]{fontenc}
\usepackage[textwidth = 15cm]{geometry}
\usepackage{lmodern, amssymb}
\usepackage{mathtools}
\usepackage{braket, relsize, nccmath}
\renewcommand\Set[1]{%
\csname Set \endcsname{\mskip-\medmuskip#1\mskip-\medmuskip}}%
\DeclareMathOperator{\disc}{disc}
\pagestyle{empty}

\begin{document}

$$V_{p}=\Set{% F\in\Phi | % \begin{medsize}\begin{array}{@{\mathsmaller{\bullet}\enspace}l@{}} p^2 \nmid \disc(F) \quad \text{if}\enspace p \neq 2\\[1ex] \disc(F)\equiv 1\pmod 4 \vee \disc(F)\equiv 8\vee 12 \pmod{16} \quad\text{if} \enspace p =2 \end{array}\end{medsize} }%$$

\end{document}


I'd avoid lengthy set descriptions; just provide two definitions for p different from 2 and for 2:

\documentclass[12pt,a4paper]{article}
\usepackage[utf8]{inputenc}
\usepackage{amsmath}
\usepackage{amssymb}

\DeclareMathOperator{\disc}{disc}

\begin{document}

We say that $\disc(F)$ is \emph{quozzy} if $\disc{F}\equiv1\pmod{4}$ or
$\disc(F)\equiv8\pmod{16}$ or $\disc(F)\equiv12\pmod{16}$; we shall use
this notion mostly for $p=2$; then we set
\begin{aligned} V_{p}&=\{\, F\in\Phi : p^2\nmid \disc(F)\,\}\quad(p\neq 2) \\ V_{2}&=\{\, F\in\Phi : \text{\disc(F) is quozzy}\,\} \end{aligned}

\end{document}


Choose a better word than “quozzy”.