moved more proofs to ordered_comm_monoid_add; introduced strict_ordered_ab_semigroup/comm_monoid_add
\documentclass[11pt,a4paper]{article}
\usepackage{graphicx}
\usepackage{isabelle,isabellesym}
\usepackage{pdfsetup}
\urlstyle{rm}
\isabellestyle{it}
\begin{document}
\title{Various results of number theory}
\maketitle
\tableofcontents
\begin{center}
\includegraphics[width=\textwidth,height=\textheight,keepaspectratio]{session_graph}
\end{center}
\newpage
\parindent 0pt\parskip 0.5ex
\input{session}
\end{document}