clarified persistent data: digest may help to synchronize files, without requiring read / uncompress;
\documentclass[11pt,a4paper]{article}
\usepackage[T1]{fontenc}
\usepackage[only,bigsqcap]{stmaryrd}
\usepackage{ifthen,proof,amssymb,isabelle,isabellesym}
\isabellestyle{literal}
\usepackage{pdfsetup}\urlstyle{rm}
\hyphenation{Isabelle}
\begin{document}
\title{Basic combinatorics in Isabelle/HOL (and the Archive of Formal Proofs)}
\maketitle
\tableofcontents
\parindent 0pt \parskip 0.5ex
\input{session}
\end{document}