\documentclass[11pt,a4paper]{article}
\usepackage{graphicx}
\usepackage{isabelle,isabellesym}
\usepackage{amssymb}
\usepackage{textcomp}
\usepackage[utf8]{inputenc}
\usepackage[only,bigsqcap]{stmaryrd}
%\usepackage{amsmath}
% this should be the last package used
\usepackage{pdfsetup}
\urlstyle{rm}
\isabellestyle{tt}
\pagestyle{myheadings}
\begin{document}
\title{The Isabelle/HOL Algebra Library}
\author{Clemens Ballarin (Editor)}
\date{With contributions by Jesús Aransay, Clemens Ballarin, Stephan Hohe,
Florian Kammüller and Lawrence C Paulson \\
\today}
\maketitle
\tableofcontents
\begin{center}
\includegraphics[scale=0.5]{session_graph}
\end{center}
\clearpage
%\renewcommand{\isamarkupheader}[1]%
%{\section{\isabellecontext: #1}\markright{THEORY~``\isabellecontext''}}
\parindent 0pt\parskip 0.5ex
\input{session}
\pagestyle{headings}
\bibliographystyle{abbrv}
\bibliography{root}
\end{document}