Refering to a theorem by its name

Question

So I've seen here that you can actually have a personnalized theorem environment name but I was wondering if there was a way to refer to it as is. I've chosen the solution

\documentclass{article}
\usepackage{amsthm}
\swapnumbers % optional, of course
\newtheorem{thm}{Theorem}[section] % the main one
\newtheorem{lemma}[thm]{Lemma}
% other statement types
\theoremstyle{plain} % just in case the style had changed
\newcommand{\thistheoremname}{}
\newtheorem{genericthm}[thm]{\thistheoremname}
\newenvironment{namedthm}[1]
  {\renewcommand{\thistheoremname}{#1}%
   \begin{genericthm}}
  {\end{genericthm}}
\begin{document}
\section{Something}
A theorem
\begin{thm}
$1+1=2$.
\end{thm}
And a named theorem
\begin{namedthm}{Zorn's Lemma}[Zermelo]\label{zorn}
All well-behaved ordered sets have maximal elements.
\end{namedthm}
\end{document}

given by @egreg and I would like to have it say "by Zorn's Lemma" when I write

by \cref{zorn}.

I know that I don't technically need it since it shouldn't be something that changes but we never know. Maybe I could link it with a hyperlink hidden under the text "Zorn's lemma"?

@samcarter_is_at_topanswers.xyz just edited the part I had forgotten — Jolia, Feb 19 '24 at 15:53

samcarter_is_at_topanswers.xyz · Answer 1 · 2024-02-19T16:12:25.550

Using the same trick as in https://tex.stackexchange.com/a/709531/36296

\documentclass{article}
\usepackage{amsthm}
\swapnumbers % optional, of course
\newtheorem{thm}{Theorem}[section] % the main one
\newtheorem{lemma}[thm]{Lemma}
% other statement types
\theoremstyle{plain} % just in case the style had changed
\newcommand{\thistheoremname}{}
\newtheorem{genericthm}[thm]{\thistheoremname}
\makeatletter
\NewDocumentEnvironment{namedthm}{ m o }
  {\renewcommand{\thistheoremname}{#1}%
   \begin{genericthm}[#2]
   \def@currentlabelname{#1}
   }
  {\end{genericthm}}
\makeatother

\usepackage{nameref}
\begin{document}
\section{Something}
A theorem
\begin{thm}
$1+1=2$.
\end{thm}
And a named theorem
\begin{namedthm}{Zorn's Lemma}[Zermelo]\label{zorn}
All well-behaved ordered sets have maximal elements.
\end{namedthm}
by \nameref{zorn}
\end{document}

score 0 · Answer 2 · answered Feb 19 '24 at 16:25

I see no need to make a big distinction between named and unnamed (but numbered) theorem-like environments. In fact, depending on the context, I think it's useful to be able to refer to a given theorem-like environment either by its number or by its name. The latter may be achieved with the help of the hyperref package and its \hypertarget/\hyperlink pair of macros.

Of course, if you create unnumbered theorems, you can still use the \hypertarget/\hyperlink mechanism to create textual cross-references to them.

\documentclass{article}
\usepackage{geometry}
\usepackage{amsthm}
\usepackage[colorlinks,allcolors=blue]{hyperref}
\usepackage[capitalize,nameinlink]{cleveref}
\newtheorem{thm}{Theorem}
\begin{document}
\begin{thm}[\hypertarget{Zorn}{Zorn's Lemma}]\label{thm:zorn}
All well-behaved ordered sets have maximal elements.
\end{thm}
By \cref{thm:zorn}, \dots
By \hyperlink{Zorn}{Zorn's Lemma}, \dots
\end{document}

Refering to a theorem by its name

2 Answers2