replaced apply-style proof for instance Multiset :: plus_ac0 by recommended Isar proof style
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%% Author: Markus Wenzel, TU Muenchen
%% License: GPL (GNU GENERAL PUBLIC LICENSE)
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%% smart url or hyperref setup
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\@ifundefined{pdfoutput}
{\usepackage{url}}
{\usepackage{color}\definecolor{darkblue}{rgb}{0,0,0.5}
\usepackage[pdftex,a4paper,colorlinks=true,linkcolor=darkblue,citecolor=darkblue,filecolor=darkblue,pagecolor=darkblue,urlcolor=darkblue]{hyperref}
\IfFileExists{thumbpdf.sty}{\usepackage{thumbpdf}}{}}