# Theorem/Definition/Lemma problem --- Numbering

I am trying to work on the numbering of the theorems/definitions/lemmas etc., and I have some problems with the numbering.

I would like the theorems, propositions, corollarys, definitions, conjectures, examples to follow the same numbering, and to reduce the numbering. For example, in my code below, the stuff goes as follows:

Chapter 1

1.1 Basics (SECTION)

Definition 1.1.1.

Theorem 1.1.1.

Theorem 1.1.2.

Example 1.1.1.

1.1.1. Some tips (SUBSECTION)

Definition 1.1.2.

Definition 1.2.1.

But how would I get it to be like this below?:

Chapter 1

1.1 Basics (SECTION)

Definition 1.1

Theorem 1.2

Theorem 1.3

Example 1.4

1.1.1. Some tips (SUBSECTION)

Definition 1.5

Definition 1.6

And for each new chapter, how would I get the numbering to be resetted? Like it would be Definition 2.1, Theorem 2.2, Theorem 2.3 for chapter 2.

I like the layout of my table of contents, i.e. Part I is addition and subtraction, Part II is Multiplication and division, and I am happy with the way the sections and subsections are working, but I just want to definitions, theorems etc. to be corrected.

\documentclass[11pt,a4paper]{report}
\usepackage{amsmath,amsfonts,amssymb,amsthm,epsfig,epstopdf,titling,url,array}

\theoremstyle{plain}
\newtheorem{thm}{Theorem}[section]
\newtheorem{lem}[thm]{Lemma}
\newtheorem{prop}[thm]{Proposition}
\newtheorem*{cor}{Corollary}

\theoremstyle{definition}
\newtheorem{defn}{Definition}[section]
\newtheorem{conj}{Conjecture}[section]
\newtheorem{exmp}{Example}[section]

\theoremstyle{remark}
\newtheorem*{rem}{Remark}
\newtheorem*{note}{Note}

\begin{document}
\tableofcontents

\section{Basics}
\begin{defn}
Here is a new definition
\end{defn}
\begin{thm}
Here is a new theorem
\end{thm}
\begin{thm}
Here is a new theorem
\end{thm}
\begin{exmp}
Here is a good example.
\end{exmp}
\subsection{Some tips}
\begin{defn}
Here is a new definition
\end{defn}
\begin{defn}
Here is a new definition
\end{defn}
\subsection{Warnings}
\begin{defn}
Here is a new definition
\end{defn}

\chapter{Subtraction}
\section{Basics}
\subsection{Some tips}
\subsection{Warnings}

\part{Multiplication and Division}

\chapter{Multiplication}
\section{Basics}
\subsection{Some tips}
\subsection{Warnings}

\chapter{Division}
\section{Basics}
\subsection{Some tips}
\subsection{Warnings}

\end{document}


Similar to the solution at this question and section 3 of the amsthm documentation:

\documentclass[11pt,a4paper]{report}
\usepackage{amsthm}

\theoremstyle{plain}
\newtheorem{thm}{Theorem}[chapter] % reset theorem numbering for each chapter

\theoremstyle{definition}
\newtheorem{defn}[thm]{Definition} % definition numbers are dependent on theorem numbers
\newtheorem{exmp}[thm]{Example} % same for example numbers

\newcommand{\chaptercontent}{
\section{Basics}
\begin{defn}Here is a new definition.\end{defn}
\begin{thm}Here is a new theorem.\end{thm}
\begin{thm}Here is a new theorem.\end{thm}
\begin{exmp}Here is a good example.\end{exmp}
\subsection{Some tips}
\begin{defn}Here is a new definition.\end{defn}
\begin{defn}Here is a new definition.\end{defn}
\subsection{Warnings}
\begin{defn}Here is a new definition.\end{defn}
}

\begin{document}
\tableofcontents
\chapter{Subtraction} \chaptercontent
\part{Multiplication and Division}
\chapter{Multiplication} \chaptercontent
\chapter{Division} \chaptercontent
\end{document}

• How to make the corollaries, lemmas, and propositions italic like theorems? Feb 20, 2022 at 16:06
• Really should be a separate question, but it may have already been answered here. Feb 21, 2022 at 23:47

You can do something like this

\newtheorem{theorem}{Theorem}
\newtheorem{claim}[theorem]{Claim}
\newtheorem{proposition}[theorem]{Proposition}
\newtheorem{lemma}[theorem]{Lemma}
\newtheorem{corollary}[theorem]{Corollary}
\newtheorem{conjecture}[theorem]{Conjecture}
\newtheorem*{observation}{Observation}
\newtheorem*{example}{Example}
\newtheorem*{remark}{Remark}

• Welcome to TeX stackexchange. Answering questions is a good thing to do. That said, how does your answer add to the accepted one? Finally, when posting questions and answers its best to include a complete compilable example, not just a code fragment. Apr 9, 2017 at 13:40
• @EthanBolker This is more simplistic than the first one! Thank you for welcoming me to TeX stackexchange Oct 18, 2018 at 16:01
• How to make the corollaries, lemmas, and propositions italic like theorems? @Trect Feb 20, 2022 at 16:06