ok heres the re edit
\documentclass[a4paper,12pt]{report}
\usepackage{amsthm}
\newtheorem{theorem}{Theorem}[section]
\newtheorem{lemma}[theorem]{Lemma}
\newtheorem{proposition}[theorem]{Proposition}
\newtheorem{corollary}[theorem]{Corollary}
\newtheorem{definition}[theorem]{Definition}
\newtheorem{remark}[theorem]{Remark}
\newtheorem{example}[theorem]{Example}
\newtheorem{notation}[theorem]{Notation}
\usepackage{amsfonts}
\usepackage{amssymb}
\usepackage{amsmath}
\usepackage{graphicx}
\newcommand{\closure}[2][3]{%
{}\mkern#1mu\overline{\mkern-#1mu#2}}
\begin{document}
\section{Schwarzschild Manifold as a Graph}
\begin{definition}
Let $m\in\mathbb{R}$ be such that $m>0$ and consider the manifold
\begin{align*}
S=\left\{(r,x)|(r,x)\in{(2m,\infty){\times}S^2} \right\}.
\end{align*}
Now equip $S$ with the Riemannian metric
\begin{align*}
g_S=\frac{1}{1-\frac{2m}{r}}dr^2+r^2d{\theta}^2+r^2{\sin\theta}^2d{\phi}^2,
\end{align*}
where $(\theta,{\phi})$ are the standard polar coordinates on $S^2$. Then we call $(S,g_S)$ the Schwarzschild manifold.
\end{definition}
\begin{chapter}
{The Positive Mass Theorem for Graphs over $\mathbb{R}^3$}
\begin{theorem}\label{positivemasstheorem}
{\textnormal{(Positive Mass Theorem for graphs over $\mathbb{R}^3$)}}
\begin{equation}{\label{positivemassthmeqn}}
m_{ADM}=\frac{1}{16\pi}\int_MR\frac{1}{\sqrt{1+|\nabla f|^2}}\,dV_g.
\end{equation}
\end{theorem}
\end{chapter}
\end{document}
i get the first section as 0.1, first defn as 0.1.1 which is okay. but when the new chapter stats, the theorem starts as 0.1.2?
{}above the text field. See our TeX.SX starter guide for more information on how the site works. – Torbjørn T. Jun 10 '13 at 18:22\sectionis renumbered from zero when the chapter changes, but\subsectionisn't -- it resets at each\section. so at the chapter break,\setcounter{subsection}{0}explicitly. – barbara beeton Jun 10 '13 at 18:554.0.1is very strange numbering to get from a report class document. – David Carlisle Jun 10 '13 at 18:59\sectionrather than\subsection– David Carlisle Jun 10 '13 at 19:00