# Reference Subpoints of Lemma

I have Lemmata consisting of several subpoints (basically a collection of similar formulas) and I want to reference these subpoints in text by "Lemma 1 (1)".

So far my code looks like this:

\documentclass[10pt,a4paper]{article}
\usepackage[utf8]{inputenc}

\usepackage{hyperref}
\newtheorem{lemma}{Lemma}
\usepackage[shortlabels]{enumitem}

\begin{document}
\begin{lemma}\label{lemma}
This is a collection of formulas
\begin{enumerate}
\item Equation 1 \label{sublemmaOne}
\item Equation 2
\end{enumerate}
\end{lemma}

A reference to the first item of the lemma \autoref{lemma}(\ref{sublemmaOne}).

\end{document}


This works somehow and I can even make a macro :

\newcommand{\refSublemmaOne}{\autoref{lemma}(\ref{sublemmaOne})}


However, I see two goals for improvement

• I would prefer it if there were a single hyperref link instead of two close to each other
• I would prefer to somehow use the usual \autoref{mylabel} syntax so on referencing I do not have to care whether I reference a normal lemma or a subpoint.

I am both open to suggestions that directly address the referencing and to ones to structure the lemma differently than by using enumerate if it is still a lemma with subpoints and that helps to solve the referencing.

When using the enumitem package you can set the format of the references with the option ref=format, see the enumitem manual page 3. In the example below the format is set to

\thelemma (\arabic*)

which prints \the value of the lemma counter followed by ( and the \arabic representation of the * (=current enumerate) counter followed by ).

Code:

\documentclass[10pt,a4paper]{article}
\usepackage[utf8]{inputenc}

\usepackage{hyperref}
\newtheorem{lemma}{Lemma}
\usepackage[shortlabels]{enumitem}

\begin{document}
\begin{lemma}
\label{mylemma}
This is a collection of formulas
\begin{enumerate}[ref=\thelemma (\arabic*)]
\item Equation 1 \label{sublemmaOne}
\item Equation 2 \label{sublemmaTwo}
\end{enumerate}
\end{lemma}

A reference to the first item of the lemma \ref{sublemmaOne} or the second item \ref{sublemmaTwo}.

\end{document}


Result: