\renewcommand{\thesection}{\arabic{section}} %{\Roman{section}}
\newtheorem{theo}{Th\'eor\`eme}\newtheorem{thdef}[theo]{Th\'eor\`eme-D\'efinition}
\newtheorem{defi}[theo]{D\'efinition}
\newtheorem{cor}[theo]{Corollaire}
\newtheorem{lem}[theo]{Lemme}
\newtheorem{pte}[theo]{Propri\'et\'e}
\newtheorem{ptedef}[theo]{Propri\'et\'e-D\'efinition}
\newtheorem{prop}[theo]{Proposition}
\newtheorem{axio}[theo]{Axiome}
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