\def\ellb{{\underline{\ell}}}
\def\omegab{{\underline{\omega}}}
\def\ab{{\underline{a}}}
\def\Db{{\underline{D}}}
\def\psib{{\underline{\psi}}}
\def\hb{{\underline{h}}}
\def\R{\mathbb{R}}
\def\Int{\displaystyle\int}
\newcommand{\floor}[1]{\left\lfloor {#1} \right\rfloor}
\def\id{\operatorname{id}}
\def\diam{\operatorname{diam}}
\def\dim{\operatorname{dim}}
\def\codim{\operatorname{codim}}
\def\det{\operatorname{det}}
\def\inv{\operatorname{inv}}
\def\rank{\operatorname{rank}}
\def\ker{\operatorname{ker}}
\def\sign{\operatorname{sign}}
\def\vp{\operatorname{vp}}
\def\supp{\operatorname{supp}}
\def\Res{\operatorname{Res}}
\def\Ext{\operatorname{Ext}}
\theoremstyle{plain}
\newtheorem{them}{定理}
\newtheorem{lem}[them]{引理}
\newtheorem{prop}[them]{命题}
\newtheorem{coro}{推论}
\newtheorem*{themm}{定理}
\theoremstyle{definition}
\newtheorem{defn}[them]{定义}
\newtheorem*{defnn}{定义}
\newtheorem*{defandnotation}{定义与记号}
\theoremstyle{remark}
\newtheorem*{exam}{例子}
\newtheorem*{sikao}{思考题}
\newtheorem*{rem}{注记}
\newtheorem*{app}{应用}
\newtheorem*{note}{{\small{附注}}}
\newtheorem*{exer}{练习}
\newtheorem*{homework}{作业说明}
\newtheorem*{wisdom}{寄语}
\nosectionnumbers
\tdef\color#1{\@@if{#1}{red}{\colour{e00000}}{\@@if{#1}{blue}{\colour{0000a0}}{\colour{#1}}}}
\newcommand{\noindent}{}
\newcommand{\customItem}[1][]{\item[#1] \refstepcounter{enum-{list-level}}}