amsbookchaptersnumberingsectioning
I'm using amsbook to write a report. I'm using \chapter{}s and \section{}s, and their numbering is fine.
However, \section{}s are numbered sequentially inside each \chapter{}, but without the indication of the \chapter{}: basically, I'm getting Section 1 instead of 1.1, and similarly Subsection 1 instead of 1.1.1.
How do I go about fixing this?
Use the first optional argument for \newtheorem:
\documentclass{book}
\usepackage{amsthm}
\newtheorem{theo}[subsubsection]{Theorem}
\newtheorem{defi}[subsubsection]{Definition}
\setcounter{secnumdepth}{3}
\begin{document}
\chapter{Test Chapter}
\section{Test Section}
\subsection{Test Subsection}
\subsubsection{Test Subsubsection}
\begin{theo}
test.
\end{theo}
\subsubsection{Test Subsubsection}
\begin{theo}
test.
\end{theo}
\begin{defi}
test.
\end{defi}
\subsubsection{Test Subsubsection}
\end{document}
I think this numbering schema can result hard to follow for readers (among other things, what if, for example, there's a theorem or a definition before a subsubsection is created?).
For the bonus point (and to make things even harder for the reader):
\documentclass{book}
\usepackage{amsthm}
\usepackage{amsmath}
\usepackage{etoolbox}
\numberwithin{equation}{subsection}
\newtheorem{theo}[subsubsection]{Theorem}
\newtheorem{defi}[subsubsection]{Definition}
\setcounter{secnumdepth}{3}
\AtBeginEnvironment{equation}{\setcounter{equation}{\value{subsubsection}}}{}{}{}
\AtEndEnvironment{equation}{\stepcounter{subsubsection}}{}{}{}
\begin{document}
\chapter{Test Chapter}
\section{Test Section}
\subsection{Test Subsection}
\subsubsection{Test Subsubsection}
\begin{theo}
test.
\end{theo}
\subsubsection{Test Subsubsection}
\begin{theo}
test.
\end{theo}
\begin{defi}
test.
\end{defi}
\begin{equation}
a=b.
\end{equation}
\subsubsection{Test Subsubsection}
\begin{equation}
c=d.
\end{equation}
\end{document}
I would rather use a simpler numbering schema:
\documentclass{book}
\usepackage{amsthm}
\usepackage{amsmath}
\newtheorem{theo}{Theorem}[chapter]
\newtheorem{defi}[theo]{Definition}
\newtheorem{prop}[theo]{Proposition}
\setcounter{secnumdepth}{3}
\begin{document}
...
\end{document}
In addition to the instruction
\numberwithin{equation}{subsection}
you need the instructions
\makeatletter
\@addtoreset{equation}{section}
\makeatother
The first instruction, \numberwithin{equation}{subsection}, resets the equation counter only when a \subsection instruction is encountered. If you have a \section instruction but no \subsection instruction, the counter named equation is not reset unless you provide an additional instruction, such as \@addtoreset{equation}{section}.
Do note that if you do want to number the equations by subsection, it's probably not a good idea to feature equations between a \section directive and that section's first \subsection instruction: at that stage, the subsection counter is still 0 (having been reset to 0 by the \section directive), leading the equation numbers to be formatted as "2.0.1" and quite likely making your readers wonder if the subsection numbered 2.0 has somehow vanished mysteriously.
\documentclass{article}
\usepackage{amsmath}
\numberwithin{equation}{subsection}
\makeatletter
\@addtoreset{equation}{section}
\makeatother
\begin{document}
\section{Section 1 Title}
\subsection{Subsection 1.1 Title}
\begin{equation} a = b \end{equation}
\begin{equation} a+2=b+2 \end{equation}
\section{Section 2 Title}
%%\subsection{Subsection 2.1 Title}
\begin{equation} r=y \end{equation}
\end{document}
Best Answer
Write the following in the preamble: