Re-defining of environments for theorems, propositions, corollaries,… etc for generating subsequent numbering

numberingtheorems

I wrote the following piece of code in order to define custom environments for propositions, corollaries, remarks, definitions, examples, lemmas,…etc .

\newcounter{mthm}
\newtheorem{mthmitalic}[mthm]{\mthmname}
\theoremstyle{definition}
\newtheorem{mthmroman}[mthm]{\mthmname}
\newcommand{\mthmname}{}

\newcommand{\varnewtheorem}[3]{%
\newenvironment{#1}[1]{%
\renewcommand{\mthmname}{#2}%
\renewcommand{\themthm}{##1}%
\csname mthm#3\endcsname
 }{\csname endmthm#3\endcsname}%
}

\varnewtheorem{theorem}{Theorem}{italic}
\varnewtheorem{corollary}{Corollary}{italic}
\varnewtheorem{definition}{Definition}{roman}
\varnewtheorem{example}{Example}{roman}
\varnewtheorem{examples}{Examples}{roman}
\varnewtheorem{proposition}{Proposition}{italic}
\varnewtheorem{remark}{Remark}{roman}

Every environment (e.g, \begin{corollary}{num} \end{corollary}) takes another argument for providing the numbering of the corollary or whatever. My questions is: can this piece of code be modified in order to provide a subsequent automatic numbering such that all environments are dependent on each other. This means that if I have a Definition 1 and a theorem after the definition, then the theorem is automatically labeled by 2.

I also want the modification to work properly whether there is a partitioning of the articles into sections and subsection or not.

I hope I revealed what I want to have pretty well.

Thanks in advanceز

Best Answer

That machinery was needed because you asked for manual numbering.

Automatic numbering works out of the box.

\documentclass{article}
\usepackage{amsmath}
\usepackage{amsthm}

\newtheorem{theorem}{Theorem}[section]
\newtheorem{corollary}[theorem]{Corollary}
% declare here other similar environments with text in italic

% from now on the defined environments will have the text in upright type
\theoremstyle{definition}
\newtheorem{definition}[theorem]{Definition}
\newtheorem{example}[theorem]{Example}

\newcommand{\s}{\oplus}
\newcommand{\ds}{\leq^{\oplus}}
\DeclareMathOperator{\im}{im}

\begin{document}

\section{Title}

\begin{definition}
This is a definition of $X\ds Y$.
\end{definition}

\begin{theorem}\label{theoremC3}
Let $M_R$ be a $C3$-module. If $M=X\s Y$ and $f:X\to Y$ is a homomorphism with 
$\ker f \ds X$, then $\im f \ds Y$.
\end{theorem}

An immediate consequence of Theorem \ref{theoremC3} is the following corollary.

\begin{corollary}\label{corollaryeasy}
Corollaries are easy.
\end{corollary}

And we can even give examples.

\begin{example}
This is an example related to Corollary~\ref{corollaryeasy}
\end{example}

\end{document}

If you want the numbering to be independent of the sectios, just remove [section] from the first \newtheorem declaration.

Related Solutions

[Tex/LaTex] Consecutive number of theorems, propositions, etc

The \newtheorem construction offers two optional arguments. The first one fixes your numbering. In this case it means that proposition should use the same counter as theorem.

\documentclass{article}

\usepackage{amsthm}
\begin{document}


\newtheorem{theorem}{Theorem}
\newtheorem{proposition}[theorem]{Proposition}

\begin{theorem}
1+1=2.
\end{theorem}

\begin{proposition}
1+2=3
\end{proposition}

\end{document}

enter image description here

[Tex/LaTex] Theorem numbering

When using either the ntheorem or the amsthm package to declare theorem-like environments, it's important to make use of the following rules of syntax when using \newtheorem:

If you want the counter of a theorem-like environment to be subordinate to, say, the section number, use a directive such as
```
\newtheorem{theorem}{Theorem}[section]
```
i.e., the option [section] (the name of the "parent counter") should come at the end.
If, on the other hand, you want the theorem-like environment (say, corollary) to share a counter with an already-existing environment (say, theorem), use the following syntax:
```
\newtheorem{corollary}[theorem]{Corollary}
```
i.e., i..e, the option [theorem] (the name of the "shared counter") should be placed between the environment name and the way the environment's name should be typeset.

The output of a full MWE:

\documentclass{article}  
\usepackage{ntheorem}

\theoremstyle{theorem} 
   \newtheorem{theorem}{Theorem}[section]
   \newtheorem{corollary}[theorem]{Corollary}
   \newtheorem{lemma}[theorem]{Lemma}
   \newtheorem{proposition}[theorem]{Proposition}
\theoremstyle{definition}
   \newtheorem{definition}[theorem]{Definition}
   \newtheorem{example}[theorem]{Example}
\theoremstyle{remark}    
  \newtheorem{remark}[theorem]{Remark}

\begin{document}
\setcounter{section}{1}

\begin{theorem} a \end{theorem}
\begin{proposition} b \end{proposition}
\begin{definition} c \end{definition}
\begin{example} d \end{example}
\begin{remark} e \end{remark}
\begin{lemma} f \end{lemma}

\end{document}

Best Answer

Related Solutions

[Tex/LaTex] Consecutive number of theorems, propositions, etc

[Tex/LaTex] Theorem numbering

Related Question