自定义定理标题

Question

我想做这样的事：

\begin{theorem}[Actual name of theorem]
This theorem states that...
\end{theorem}

并且它应该呈现：

Actual name of theorem. This theorem states that...

我通过创建类似定理的环境改变了定理的名称，但我想在线执行此操作，而不创建新的环境。

Answer 1

从问题中无法明确不一方面需要创造新的环境，另一方面多种的将为每个单独命名的定理创建一个新的环境。

假设是后者，也许是这样的？

\documentclass{book}

\usepackage{amsthm}
\usepackage{thmtools}

\declaretheorem[name=Theorem,numberwithin=chapter]{theorem}

\makeatletter
\declaretheoremstyle[
  headfont=\bfseries,
  headindent=-0.25em,
  postheadspace=0.5em,
  notefont=\bfseries, 
  notebraces={}{},
  headformat=\NOTE\thmt@space\NUMBER,
  bodyfont=\mdseries\itshape,
  spaceabove=12pt,spacebelow=12pt,
]{namedthmstyle}
\makeatother

\declaretheorem[
  style=namedthmstyle,
  name=Theorem,
  title = {},
  numberlike=theorem
]{namedtheorem}

\begin{document}

\chapter{The whole thing}

\begin{namedtheorem}[Theorem of Pythagoras]

The square on the hypotenuse of a right triangle equals the sum of the squares other two sides.

\end{namedtheorem}

\begin{namedtheorem}[Fermat's Last Theorem]

For $n > 2$, there are no positive integers $a, b, c$ for which $a^{n} + b^{n} = c^{n}$.

\end{namedtheorem}

\end{document}

请注意，我必须namedtheorem使用 来“假装”使名称排版与左边距基本齐平headindent=-0.25em。当然，还有更好、更精确的方法来实现这一点。