[Tex/LaTex] alternative to \paragraph in amsart

amsartsectioningsections-paragraphs

I have a mathematical proof which is long so I have split it up into different sections using \paragraph (eg. \paragraph{The first step}…)

In article mode, the text in the paragraph command is bolded and it stands out. In amsart, it does not and is useless. Can someone recommend me something standard I can use instead? I know I could manually bold the text but I'd rather do something standard.

I don't want to use a description environment because it indents everything and my equations break badly. Thank you.

Here is my code:

\documentclass[10pt,a4paper, reqno, draft]{amsart}
\usepackage{amsmath, color, natbib}
\usepackage{amsfonts, mathtools}
\usepackage{amssymb}
\usepackage{amsthm}
\usepackage[colorlinks=true]{hyperref}
%\usepackage[amsmath, amsthm, hyperref]{ntheorem}
\usepackage[left=2cm,right=2cm,top=2cm,bottom=2cm]{geometry}
\DeclareMathOperator*{\esssup}{ess\,sup}
\swapnumbers
\newtheorem{theorem}{Theorem}[section]
\newtheorem{defn}[theorem]{Definition}
\newtheorem{lem}[theorem]{Lemma}
\newtheorem{conjecture}[theorem]{Conjecture}
\newtheorem{remark}[theorem]{Remark}

\DeclareMathOperator{\sign}{sign}
\newcommand{\cts}{\hookrightarrow}
\newcommand{\compact}{\xhookrightarrow{c}}
\newcommand{\mvec}[2]{\begin{pmatrix}#1\\\vdots\\#2\end{pmatrix}}
\setcounter{secnumdepth}{3}
\begin{document}
\title{AA}
\author{AA}
\begin{abstract}
Blah
\end{abstract}
\maketitle
\tableofcontents
\makeatletter
\def\paragraph{\@startsection{paragraph}{4}%
  \z@\z@{-\fontdimen2\font}%
  \normalfont\bfseries}
\makeatother
\section{Introduction}
\begin{theorem}We have $a=b$.
\end{theorem}
\begin{proof}The proof is split into two.
\paragraph{First step}Blah blah blah.
\paragraph{Second step}Blah blah blah
\end{proof}

\bibliographystyle{plain}
\bibliography{AA}
\end{document}

Best Answer

amsart.cls has

\def\paragraph{\@startsection{paragraph}{4}%
  \z@\z@{-\fontdimen2\font}%
  \normalfont}

so if you put

\makeatletter
\def\paragraph{\@startsection{paragraph}{4}%
  \z@\z@{-\fontdimen2\font}%
  {\normalfont\bfseries}}
\makeatother

in your preamble, it will use bold for paragraph heads.

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