使用 amsthm 和 thmtools 继续早期的类定理环境

Question

使用 时amsthm，我希望能够在稍后继续特定的类定理环境（在我的情况下是示例）。继续的环境应具有与之前继续的环境相同的编号；并且在继续的环境完成后，应恢复正常的定理编号。

下面的方法可以实现我想要的效果。有没有更简单或更好的方法——而不必从 LaTeX 转向纯 TeX？

% continue-thm.try
\documentclass[12pt]{article}

\usepackage{amsthm}
\newtheorem{theorem}{Theorem}[section]
\newtheorem{proposition}[theorem]{Proposition}
\theoremstyle{definition}
\newtheorem{example}[theorem]{Example}

\newcounter{savedthmcounter}
\newcounter{tobecontinuedthmcounter}

% Invoke \tobecontinued immediately AFTER theorem to be continued
\newcommand{\tobecontinued}{%
    \setcounter{tobecontinuedthmcounter}{\value{theorem}}%
    \addtocounter{tobecontinuedthmcounter}{-1}}
% Invoke \continue immediately BEFORE continuing theorem that was to be continued
\newcommand{\continue}{%
    \setcounter{savedthmcounter}{\value{theorem}}%
    \setcounter{theorem}{\value{tobecontinuedthmcounter}}}
% Invoke immediately AFTER done with the continued theorem
\newcommand{\resume}{\setcounter{theorem}{\value{savedthmcounter}}}

\begin{document}

\begin{theorem}% 1
Theorem 1.
\end{theorem}

\begin{example}% 2
\label{ex:ex2}
An example.
\end{example}
%
\tobecontinued

\begin{theorem}% 3
Theorem 3.
\end{theorem}

\begin{theorem}%4
Theorem 4.
\end{theorem}

\begin{proposition}
A proposition.
\end{proposition}

\continue
%
\begin{example}[continued]% 2 again
Example \ref{ex:ex2}, continued.
\end{example}

\resume

\begin{theorem}% 5
Theorem 5.
\end{theorem}

\end{document}

添加

前面的方法不仅适用于amsthm与article等，而且当我使用thmtools和然后\declaretheoremstyle和\declaretheorem（并且，碰巧，与memoir我正在使用的类）时也有效。

我如何调用thmtools包的\declaretheoremstyle和\declaretheorem（使用memoir）以适应建议的答案 - 尤其是egreg的答案？

更新：如果要继续的类定理环境已经有注释（即来自类似\begin{example}[some text]），那么似乎需要一种不同于上述和下面接受的答案的方法。其中一种方法显示在https://tex.stackexchange.com/a/702575/13492。

Answer 1

我认为你不需要如此复杂的框架：我只能想到继续举例。

\documentclass[12pt]{article}

\usepackage{amsthm}

\newtheorem{theorem}{Theorem}[section]
\newtheorem{proposition}[theorem]{Proposition}

\theoremstyle{definition}
\newtheorem{example}[theorem]{Example}
\newtheorem*{excont}{Example \continuation}
\newcommand{\continuation}{??}
\newenvironment{continueexample}[1]
 {\renewcommand{\continuation}{\ref{#1}}\excont[continued]}
 {\endexcont}

\begin{document}

\begin{theorem}% 1
Theorem 1.
\end{theorem}

\begin{example}% 2
\label{ex:ex2}
An example.
\end{example}

\begin{theorem}% 3
Theorem 3.
\end{theorem}

\begin{theorem}%4
Theorem 4.
\end{theorem}

\begin{proposition}
A proposition.
\end{proposition}

\begin{continueexample}{ex:ex2}
Example \ref{ex:ex2}, continued.
\end{continueexample}

\begin{theorem}% 5
Theorem 5.
\end{theorem}

\end{document}

只需为您想要继续的示例提供\label，并将其用作的参数continueexample。

没有thmtools什么不同，只要记住使用\protect\continuation。

\documentclass[12pt]{article}

\usepackage{amsthm}
\usepackage{thmtools}

\declaretheoremstyle[
  bodyfont=\upshape,
]{upshape}

\declaretheorem[
  name=Theorem,
  within=section,
]{theorem}
\declaretheorem[
  name=Proposition,
  sibling=theorem,
]{proposition}
\declaretheorem[
  style=upshape,
  name=Example,
  sibling=theorem,
]{example}
\declaretheorem[
  style=upshape,
  name=Example \protect\continuation,
  unnumbered,
]{excont}
\newcommand{\continuation}{??}
\newenvironment{continueexample}[1]
 {\renewcommand{\continuation}{\ref{#1}}\excont[continued]}
 {\endexcont}


\begin{document}

\begin{theorem}% 1
Theorem 1.
\end{theorem}

\begin{example}% 2
\label{ex:ex2}
An example.
\end{example}

\begin{theorem}% 3
Theorem 3.
\end{theorem}

\begin{theorem}%4
Theorem 4.
\end{theorem}

\begin{proposition}
A proposition.
\end{proposition}

\begin{continueexample}{ex:ex2}
Example \ref{ex:ex2}, continued.
\end{continueexample}

\begin{theorem}% 5
Theorem 5.
\end{theorem}

\end{document}

Answer 2

基于https://tex.stackexchange.com/a/311985/36296您可以创建一个新环境，自动从标签中获取上一个示例编号，并在继续示例后重置它。这将

• 省去手动添加的麻烦\tobecontinued，\continue\resume

• 适用于每个示例，而不仅仅是最后一个标有\tobecontinued

---

% continue-thm.try
\documentclass[12pt]{article}

\usepackage{amsthm}
\newtheorem{theorem}{Theorem}[section]
\newtheorem{proposition}[theorem]{Proposition}
\theoremstyle{definition}
\newtheorem{example}[theorem]{Example}

\newcounter{savedthmcounter}
\newcounter{tobecontinuedthmcounter}

\makeatletter
\def\@extractthmnum#1.#2{#2}
\newcommand{\extractthmnum}[2]{% \extractthmnum{<cnt>}{<ref>}
  \setcounter{#1}{0}% Default
  \ifcsname r@#2\endcsname
    \edef\@tempa{\csname r@#2\endcsname}% Extract complete reference
    \edef\@tempa{\expandafter\@firstoftwo\@tempa}% Extract number
    \setcounter{#1}{\expandafter\@extractthmnum\@tempa}% Strip number
  \fi
}
\makeatother

\newenvironment{excont}[1][]{
    \extractthmnum{tobecontinuedthmcounter}{#1}
    \addtocounter{tobecontinuedthmcounter}{-1}
     \setcounter{savedthmcounter}{\value{theorem}}
    \setcounter{theorem}{\value{tobecontinuedthmcounter}}
    \begin{example}[continued]
}{
\end{example}
\setcounter{theorem}{\value{savedthmcounter}}
}

\begin{document}

\begin{theorem}% 1
Theorem 1.
\end{theorem}

\begin{example}% 2
\label{ex:ex2}
An example.
\end{example}


\begin{theorem}% 3
Theorem 3.
\end{theorem}

\begin{theorem}%4
Theorem 4.
\end{theorem}

\begin{proposition}
A proposition.
\end{proposition}

\begin{excont}[ex:ex2]% 2 again
Example \ref{ex:ex2}, continued.
\end{excont}


\begin{theorem}% 5
Theorem 5.
\end{theorem}

\end{document}