Using page counter in \newtheorem

Question

I would like to use the page counter as a the first part of the label for definitions. I tried

\newtheorem{definition}{Definition}[page]

but that wouldn't work if the definition is at the top of a new page, presumably because of this. Is there any way around it?

Answer 1

You can use the perpage package:

\documentclass{article}
\usepackage{amsthm,perpage,etoolbox}

\theoremstyle{definition}
\newtheorem{definition}{Definition}
\MakePerPage{definition}
\renewcommand{\thedefinition}{\theperpage.\arabic{definition}}
% We encourage TeX to break before a definition so the numbering will be correct
\BeforeBeginEnvironment{definition}{\goodbreak}

\usepackage[paperheight=60pt]{geometry} % just for the example

\begin{document}
\begin{definition}
First on first page
\end{definition}

\begin{definition}
Second on first page
\end{definition}

\newpage

\begin{definition}
First on second page
\end{definition}
\end{document}

This will assign numbers 1.1, 1.2 and 2.1