# Proposition command doesn't work

Please refer to the below code:

\documentclass[a4paper,11pt]{report}
\usepackage{a4wide}
\usepackage{amsmath}
\usepackage{amssymb}
\usepackage{graphicx}
\usepackage{url}
\usepackage{fixltx2e}
\usepackage{caption}
\usepackage{subcaption}
\oddsidemargin 0.0in
\textwidth 6.27in
\topmargin -0.5in
\textheight 9.69in
\footskip 0.5in
\urlstyle{sf}
\usepackage{fancyhdr}
\makeatletter
\newcommand*{\rom}[1]{\expandafter\@slowromancap\romannumeral #1@}
\makeatother
\usepackage{epstopdf}
\usepackage{multirow}
\usepackage{subfig}
\linespread{1.3}
\usepackage{float}
\usepackage{enumerate}
\usepackage{enumitem}
\usepackage{multirow}
\usepackage{amsmath, amsthm, amssymb}

\begin{document}
\begin{prop}
1. $x=Y+z$ \\
2. $\alpha=1-x$
\end{prop}
\end{document}

• you really don't need to load the packages amsmath and amssymb twice. (order doesn't matter here, so just put them wherever you find easiest to remember.) – barbara beeton Jul 30 '13 at 15:58

## 1 Answer

You need to define the structure using \newtheorem (refer to the documentation of the amsthm package for further details on the optional arguments of this command):

\documentclass[a4paper,11pt]{report}
\usepackage{amsmath, amsthm, amssymb}

\newtheorem{prop}{Proposition}

\begin{document}
\begin{prop}
\begin{enumerate}
\item $x=Y+z$
\item $\alpha=1-x$
\end{enumerate}
\end{prop}
\end{document}


Not related to the question, but I replaced you manual enumeration with an enumerate environment. You are loading some packages more than once; this should be avoided. Also changes to the page layout should be better done using the geometry package.

• How about for the lemmas. Let say i want to write a lemma – Norman Jul 30 '13 at 2:40
• @Norman Same idea: in the preamble: \newtheorem{lemm}{Lemma}, and then in the document \begin{lemm} contents\end{lemm}. – Gonzalo Medina Jul 30 '13 at 2:47
• And if you want the text to be upright, not italicized, you can always add \theoremstyle{definition}\newtheorem{rant}{Angry Rant}. More examples may be found in the AMSthm documentation. – Alex Nelson Jul 30 '13 at 3:35
• Seems that the a4wide package is no longer supported. You should use the geometry package. and give a4 as an option. cheers – wierts Jul 30 '13 at 8:25
• @GonzaloMedina if i have a lemma with sections, As an example Lemma 1, Lemma 1.1 and Lemma 1.2 like wise, what would be the latex command? – Norman Jul 31 '13 at 3:02