[Tex/LaTex] Common, per-section numbering of theorems, lemmas etc.

numberingtheorems

I use amsthm for my theorems, lemmas etc.

I'd like their numbering to look like that:

Theorem 1.1.1
Lemma 1.1.2
Definition 1.1.3
Theorem 1.2.1
Definition 1.2.2
Corollary 1.2.3
Theorem 2.1.1
etc.

To make the numbering "per-section" I did

\newtheorem{defi}{Definition}[section]

But then each theorem type I defined had its own counter. So I tried

\newtheorem{defi}[somecounter]{Definition}

But then the numbers are just plain, section part disappears!

So I'd like to write something like

\newcounter{somecounter}[section]
\newtheorem{defi}[somecounter]{Definition}[section]

But this doesn't work 🙁

How can I achieve such effect?

Best Answer

You need to make a "dummy" theorem and make all the others subordinate to that. For example:

\documentclass{article}
\usepackage{amsthm,amsmath}
% \newtheorem{dummy}{Dummy}[section]
\newcounter{dummy} \numberwithin{dummy}{section}
\newtheorem{thm}[dummy]{Theorem}
\newtheorem{defn}[dummy]{Definition}
\begin{document}

\section{First}

 \begin{thm}
 \end{thm}

 \begin{defn}
 \end{defn}

\section{Second}

 \begin{thm}
 \end{thm}

 \begin{defn} 
 \end{defn}

\end{document}

Either the commented \newtheorem line or the \newcounter line works; the \numberwithin command is defined by amsmath, but if you are using amsthm you are probably using that too. If not, then the \newtheorem line works just with amsthm.

Related Solutions

[Tex/LaTex] Theorem/Definition/Lemma problem — Numbering

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

enter image description here

\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}
\section{Advanced stuff}
\begin{defn}Here is a new definition.\end{defn}
\subsection{Warnings}
\begin{defn}Here is a new definition.\end{defn}
}

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

[Tex/LaTex] Common numbering with ntheorem

From your code, it seems that you want each of the theorem-like environments to inherit the subsection counter. As such, I have used

\newcounter{dummy} 
\numberwithin{dummy}{subsection}

in the below.

Note that you can use

\newtheorem{example}[dummy]{Example}

which tells the newtheorem command to make the example counter inherit the dummy counter, but not

\newtheorem{example}{Example}[dummy][subsection]

as this is undefined.

screenshot

Here's the complete MWE:

\documentclass{article}

\usepackage{amsmath,amssymb}
\usepackage[thmmarks]{ntheorem}

\newcounter{dummy}
\numberwithin{dummy}{subsection}

\theoremprework{\setlength
\theorempreskipamount{10 pt}\setlength\theorempostskipamount{10 pt}}

\theoremstyle{plain}
\theorembodyfont{\upshape}
\theoremsymbol{\ensuremath{\clubsuit}}
\theoremseparator{:}
\newtheorem{example}[dummy]{Example}

\theoremstyle{plain}
\theorembodyfont{\upshape}
\theoremsymbol{\ensuremath{\blacklozenge}}
\theoremseparator{:}
\newtheorem{remark}[dummy]{Remark}

\theoremprework{\setlength\theorempreskipamount{10 pt}}

\theoremstyle{plain}
\theorembodyfont{\slshape}
\theoremsymbol{}
\theoremseparator{:}
\newtheorem{theorem}[dummy]{Theorem}

\theoremstyle{plain}
\theorembodyfont{\slshape}
\theoremsymbol{}
\theoremseparator{:}
\newtheorem{prop}[dummy]{Proposition}


\theoremstyle{plain}
\theoremheaderfont{\upshape \bfseries}
\theorembodyfont{\slshape}
\theoremsymbol{}
\theoremseparator{:}
\newtheorem{corollary}[dummy]{Corollary}

\theoremstyle{plain}
\theoremheaderfont{\upshape \bfseries}
\theorembodyfont{\slshape}
\theoremsymbol{}
\theoremseparator{:}
\newtheorem{lemma}[dummy]{Lemma}

\begin{document}

\section{Section}
\subsection{SubSection}
\begin{theorem} Hey
\end{theorem}

\begin{lemma}I
\end{lemma}

\begin{prop}Just
\end{prop}

\begin{remark}Met
\end{remark}

\begin{example}You
\end{example}

\subsection{SubSection}
\begin{theorem} Hey
\end{theorem}

\begin{lemma}I
\end{lemma}

\begin{prop}Just
\end{prop}

\begin{remark}Met
\end{remark}

\begin{example}You
\end{example}
\end{document}

Best Answer

Related Solutions

[Tex/LaTex] Theorem/Definition/Lemma problem — Numbering

[Tex/LaTex] Common numbering with ntheorem

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