15 LaTeX 如何修改定理环境中的具体的定理名不由小括号包裹并后接冒号？

本弹性强迫症也来给一个briefly summary:
参考自tse上的另一个回答，大致有以下三种方案：

• amsthm宏包
• ntheorem宏包
• thmtools宏包

方案一：

\documentclass{ctexart}
\usepackage{amsmath}
\usepackage{amsthm}
\usepackage{lipsum,zhlipsum}
\newtheoremstyle{no-bracket}
    {\topsep}
    {\topsep}
    {\normalfont\itshape}
    {0pt}
    {\bfseries}
    {} %{:}
    {\newline}
    %{\thmname{#1}~\thmnumber{#2}\thmnote{ \textlangle#3\textrangle}}
    {\thmname{#1}~\thmnumber{#2}\thmnote{ #3: }}
\theoremstyle{no-bracket}  
\newtheorem{theorem}{定理}[section]
\begin{document}
\noindent 使用\verb|amsthm|宏包的\verb|\newtheoremstyle|修改参数\verb|<CUSTOM-HEAD-SPEC>|实现

\section{这是一个章节}
\begin{theorem}[Fundamental Theorem of Algebra]
    \lipsum[2]
\end{theorem}
\begin{theorem}[代数学基本定理]
    Fundamental Theorem of Algebra
\end{theorem}
\begin{theorem}[代数学基本定理]
    \zhlipsum[1]
\end{theorem}
\end{document}

方案二：

\documentclass[12pt]{ctexart}
\usepackage{amsmath}
\usepackage{lipsum,zhlipsum}
\usepackage{ntheorem}
\makeatletter
\newtheoremstyle{no-bracket}
  {
    \item[
        \rlap{\vbox{\hbox{\hskip\labelsep 
        \theorem@headerfont ##1\ ##2\theorem@separator}
        \hbox{\strut}}}
    ]
  }%
  {
    \item[
        \rlap{\vbox{\hbox{\hskip\labelsep 
        \theorem@headerfont ##1\ ##2\ ##3: \theorem@separator}\hbox{\strut}}}
        %冒号加在这里不会有空格
    ]
}
\makeatother
\theoremstyle{no-bracket}
%\theoremseparator{:} %出现空格
\newtheorem{theorem}{Theorem}

\begin{document}
\noindent 使用\verb|ntheorem|宏包的\verb|\newtheoremstyle|命令

\section{这是一个章节}
\begin{theorem}[Fundamental Theorem of Algebra]
    \lipsum[2]
\end{theorem}
\begin{theorem}[代数学基本定理]
    Fundamental Theorem of Algebra
\end{theorem}
\begin{theorem}[代数学基本定理]
    \zhlipsum[1]
\end{theorem}
\end{document}

方案三：

\documentclass[10pt,a4paper]{ctexart}
\usepackage{amsmath}
\usepackage{amsthm}
\usepackage{lipsum,zhlipsum}
\usepackage{thmtools} %
\declaretheoremstyle[
  spaceabove=\topsep, 
  spacebelow=\topsep,
  headfont=\normalfont\bfseries,
  notefont=\bfseries, 
  notebraces={}{},
  bodyfont=\normalfont\itshape,
  postheadspace=\newline,
  headpunct={:},
]{no-bracket}
\declaretheorem[style=no-bracket,name=Theorem]{theorem}

\begin{document}
\noindent 使用\verb|thmtools|宏包的\verb|\declaretheoremstyle|命令设置

\section{这是一个章节}
\begin{theorem}[Fundamental Theorem of Algebra]
    \lipsum[2]
\end{theorem}
\begin{theorem}[代数学基本定理]
    Fundamental Theorem of Algebra
\end{theorem}
\begin{theorem}[代数学基本定理]
    \zhlipsum[1]
\end{theorem}
\end{document}