# Titles become 'unbolded' when adding in a new theoremstyle

Up until now, whenever I create a new definition or theorem etc., the title (so the word 'Definition' etc.) would come up in bold. However, when I try to add '\theoremstyle{remark}', the titles stop coming up in boldface. Is there any way I can fix this (i.e. so I don't have to bold each title individually as it comes up)? Sorry if this is a stupid question, I'm very new to all this.

• Yes there is. \theoremstyle sets how theorems will be printed from that point onward, so setting it to something like remark (which doesn't have a bold title will have exactly that effect. Could you provide the community with a use-case in the form of a minimal working example (MWE)? – Werner Dec 11 '14 at 0:50
• Welcome to TeX.SX! You can have a look at our starter guide to familiarize yourself further with our format. – cfr Dec 11 '14 at 0:52
• Ah, so at the moment I have the following: \theoremstyle{definition} \theoremstyle{theorem} \theoremstyle{corollary} \theoremstyle{proposition} \theoremstyle{lemma} \theoremstyle{example} \theoremstyle{remark} \newtheorem{definition}{Definition}[section] \newtheorem{theorem}{Theorem}[section] \newtheorem{corollary}{Corollary}[section] \newtheorem{proposition}{Proposition}[section] \newtheorem{lemma}{Lemma}[section] \newtheorem{example}{Example}[section] \newtheorem{remark}{Remark}[section] As remark is one of them, does this make all my theorem non bold? – user112495 Dec 11 '14 at 0:54
• Which theorem package do you use? – Bernard Dec 11 '14 at 1:00
• @Bernard amsthm – user112495 Dec 11 '14 at 1:01

You should use them like this.

\documentclass{article}
\usepackage{amsmath,amsthm}

\newtheorem{theorem}{Theorem}[section]
\newtheorem{corollary}{Corollary}[section]
\newtheorem{proposition}{Proposition}[section]
\newtheorem{lemma}{Lemma}[section]
\newtheorem{example}{Example}[section]
\theoremstyle{definition}
\newtheorem{definition}{Definition}[section]
\theoremstyle{remark}
\newtheorem{remark}{Remark}[section]
\begin{document}
\begin{definition}
This is a definition
\end{definition}
\begin{theorem}
This is a theorem
\end{theorem}
\begin{corollary}
This is a corollary
\end{corollary}
\begin{proposition}
This is a proposition
\end{proposition}
\begin{lemma}
This is a lemma
\end{lemma}
\begin{example}
This is an example
\end{example}
\begin{remark}
This is a remark
\end{remark}
\end{document}


• the recommended style for a definition is \theoremstyle{definition}, which sets the text in roman. more information regarding the three styles defined by amsthm (although not the type style used for the headings) is given in this answer: Non italic text in theorems, definitions, examples – barbara beeton Dec 11 '14 at 15:12
• @barbarabeeton Right. – user11232 Dec 11 '14 at 15:27