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This code produces the error "! LaTeX Error: Something's wrong--perhaps a missing \item.See the LaTeX manual or LaTeX Companion for explanation.Type H for immediate help.... \end{lem}". I really don't know why because I am not even using the itemize environment. It works fine if i remove the figure, which confuses me even more. Please help me, I am lost right now! Thanks!!!


\usepackage[utf8]{inputenc}
\usepackage[T1]{fontenc}
\usepackage[ngerman]{babel}
\usepackage{graphicx}
\graphicspath{ {./Bilder/} }
\usepackage{amsmath} 
\usepackage{amssymb}
\usepackage{amsthm}
\usepackage{amsbsy}
\usepackage{enumerate}
\usepackage{float}
\usepackage{hyperref}
\usepackage{listings}
\usepackage{mathtools}
\usepackage{mathrsfs}
\usepackage{subcaption}
\usepackage{xcolor}
\theoremstyle{plain}
\newtheorem{prop}{Proposition}[subsection]
\newtheorem{satz}[prop]{Satz}
\newtheorem{lem}[prop]{Lemma}
\theoremstyle{definition}
\newtheorem{defi}[prop]{Definition}
\newtheorem{bsp}[prop]{Beispiel}
\DeclareMathOperator{\arccosh}{arccosh}

\date{23.03.20}
\title{natürlicher Lebensraum des Bull's Eye}

\begin{document}
\maketitle
\tableofcontents
\newpage

\begin{figure}[H]
\includegraphics[scale=1]{fünfKreise1}
\center
\caption{Lösung für Krümmung $d_2= a+b+c - 2 \sqrt{ab+ac+bc}$}
\label{abb:fünfKreise1}
\end{figure}
\subsection{Ringinvarianz}
$d$ ganze Zahl $\Leftrightarrow \exists q \in \mathbb{Z}, 4(ab+ac+bc)=q^2$.

\begin{lem}
Sei $R$ kommutativer Ring (mit 1 ?), $a,b,c,q \in R$ mit $$ab+ac+bc=q^2,$$ dann gilt für $d:= a+b+c+2q$, dass $p \in R$ existiert mit $$ab+ad+bd=p^2.$$
\end{lem}

\begin{proof}
\begin{align*}
ab+ad+bd&=ab + (a+b+c+2q)(a+b)\\
&=3ab+bc+ac+a^2+b^2+2aq+2bq\\
&=q^2 +a^2 +b^2+ 2ab +2aq+2bq\\
&=(q+a+b)^2
\end{align*}
\end{proof}

\end{document}```
2
  • Welcome to TeX SX! What's your document class?
    – Bernard
    Nov 18, 2020 at 14:37
  • \center inside the figure environment should be \centering.
    – leandriis
    Nov 18, 2020 at 14:56

1 Answer 1

1

Here's a minimal example:

\documentclass{article}
\usepackage{amsthm}

\newtheorem{prop}{Proposition}

\begin{document}

\begin{figure}
\center
\end{figure}

\begin{prop}
Sei $R$
\end{prop}

\end{document}

If you remove amsthm, the run is OK, but the conceptual error remains: the command \center must never be used in the document body; it can only be used for defining new environments.

What you're looking for is \centering and, of course, before \includegraphics:

\begin{figure}[htp]
\centering

\includegraphics[scale=1]{fünfKreise1}

\caption{Lösung für Krümmung $d_2= a+b+c - 2 \sqrt{ab+ac+bc}$}
\label{abb:fuenfKreise1}

\end{figure}

Avoid special characters in labels that might cause later problems.

Also load hyperref last.

1
  • Thank you very much!! ^_^ it works just fine now Nov 24, 2020 at 9:17

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