[Tex/LaTex] one counter for multiple theorems

counterssectioningtheorems

I searched the internet for a while now but didn't quite get what i wanted.
I want number different theorems with the same counter, which depends on chapter and section. eg Lemma 1.1.1 Example 1.1.2 Proof 1.1.3…
I tried to define a counter like this but i get an error which says missing \begin{document} for the setcounter command but when i put it inside the document it doesn't work neither.

\documentclass[12pt]{report}

\newcounter{cnt}[section]
\newcounter{thmcount}    
\setcounter{thmcount}{\thechapter.\thesection.\thecnt}

\newtheorem{lem}{Lemma}[thmcount]
\newtheorem{eg}{Example}[thmcount]
\newtheorem{pro}{Proof}[thmcount]

\begin{document}

\chapter{abc}
\section{xyz}

\begin{lem}
asdf
\end{lem}

\begin{eg}
fdsa
\end{eg}

\begin{pro}
sdaf
\end{pro}

\end{document}

Best Answer

There's no need to define a new counter:

\documentclass[12pt]{report}

\newtheorem{lem}{Lemma}[section]
\newtheorem{eg}[lem]{Example}
\newtheorem{pro}[lem]{Proof}

\begin{document}

\chapter{abc}
\section{xyz}

\begin{lem}
asdf
\end{lem}

\begin{eg}
fdsa
\end{eg}

\begin{pro}
sdaf
\end{pro}

\end{document}

The first \newtheorem sets up a new counter called lem (tied to section) that then is shared by all subsequent environments created with lem as optional argument just after the environment's name.

Related Solutions

[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}

[Tex/LaTex] Setting Counters for Theorems

Since you have defined the lemma structure using

\newtheorem{lemma}[theorem]{Lemma}

this implies that lemmas will share the counter for theorems and, unfortunately, the question doen't give information about how exactly the theorem structure was defined. Seeing the form of the counter, however, one can guess that the definition for theorems must be something along the lines of

\newtheorem{theorem}{Theorem}[section]

where, instead of [section] it could be [chapter] or similar. In this case, the representation for the counter for lemmas will have a prefix: the counter declared in the second optional argument for theorems and this is the counter you have to change:

\documentclass{article}
\usepackage{amsthm}

\newtheorem{theorem}{Theorem}[section]
\newtheorem{lemma}[theorem]{Lemma}

\begin{document}

\begin{lemma}
test
\end{lemma}

\setcounter{section}{5}
\begin{lemma}
test
\end{lemma}

\end{document}

enter image description here

Best Answer

Related Solutions

[Tex/LaTex] Common numbering with ntheorem

[Tex/LaTex] Setting Counters for Theorems

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