Together with another author, I am currently writing a paper using the amsart document class. We've added both of us as authors using the \author command. A third person, who is not an author of the main part of the paper, contributes an appendix. We would like to add a phrase like "with an appendix by ..." to the titlepage to mention him as the author of the appendix.
How to do this properly?
I've seen others include the phrase in the title, which I don't find optimal.
The example below corresponds quite well to what I want. I have created it using the following primitive hack:
\documentclass{amsart}
\usepackage{lipsum}
\author{Alice Foo}
\author{Bob Bar\smallskip\\
\MakeLowercase{with an appendix by} Foo Bar}
\title{This is the title}
\begin{document}
\begin{abstract}
This is the abstract.
\end{abstract}
\maketitle
\section{Introduction}
\lipsum[1]
\appendix
\section{This is the appendix title}
\smallskip
\begin{center}by \textsc{Foo Bar}\end{center}
\medskip
\lipsum[1]
\end{document}
