# How can I write a “definition” like this?

The theorem of the picture is written in bold, I mean: Theorem 1.2 (Pythagorean theorem). I want to write a definition with that format. Also, it would be better if it's written with small capitals. Beforehand, thank you.

Have a look at the amsthm package. It lets you do things like

\documentclass{article}

\usepackage{amsthm}

\newtheorem{defn}{Definition}

\begin{document}

\begin{defn}[\scshape Definition]
A definition is a definition.
\end{defn}

\end{document}


If you want to change the appearance, you can either use one of the three predefined theorem styles in amsthm, or use \newtheoremstyle to create your own one like so:

\documentclass{article}

\usepackage{amsthm}
\usepackage[T1]{fontenc}

\newtheoremstyle{mijail}
{3pt}
{3pt}
{\itshape}
{}
{\bfseries}
{}
{.5em}
{\thmname{#1} \thmnumber{#2} \thmnote{(\scshape #3)}}

\theoremstyle{mijail}
\newtheorem{defn}{Definition}

\begin{document}

\begin{defn}[Definition]
A definition is a definition.
\end{defn}

\end{document}


Note that your standard font might not include bold small caps, hence the use of \usepackage[T1]{fontenc}.

• Thank you, it is exactly what I wanted – Mijail Littin May 27 '19 at 17:25