[Tex/LaTex] How to make all the theorem-alike environments have an ending symbol

symbolstheorems

I have a question about making an ending symbol.

It is a LaTex-default that every proof environment has an ending symbol. I want to make every theorem-alike environment such as the example environment have also an ending symbol. But how to manually set this up? Specifically, I want to make all these environments ended by a square symbol.

\newtheorem{thm}{Theorem}
\newtheorem{lem}[thm]{Lemma}
\newtheorem{cor}[thm]{Corollary}
\newtheorem{pro}[thm]{Proposition}
\newtheorem{assump}{Assumption}
\newtheorem{axiom}{Axiom}
\newtheorem*{conj}{Conjecture}
\theoremstyle{definition}
\newtheorem{defi}[thm]{Definition}
\newtheorem{exam}{Example}
\newtheorem{exer}{Exercise}
\newtheorem*{rem}{Remark}
\newtheorem*{notation}{Notation}
\newtheorem*{note}{Note}

I am looking for, with gratitude, a comprehensive setup.

Best Answer

Asssume you are using \newtheorem from amsthm. Here \newtheorem defines new theorem-alike environments and ends them by \@endtheorem. The later is originally defined as \def\@endtheorem{\endtrivlist\@endpefalse } and you can insert your ending symbol here.

\documentclass{article}
\usepackage{amsthm}
\usepackage{manfnt}
\makeatletter
    \def\@endtheorem{\hfill\dbend\endtrivlist\@endpefalse }
\makeatother
\begin{document}
    \newtheorem{thm}{Theorem}
    \begin{thm}
        Zigzagging is dangerous.
    \end{thm}
\end{document}

(Ideas come form here)

Caution!

As mentioned by egreg and barbara beeton below, this construction is not perfect. Neither it is as good as the proof environment from amsmath. One of the fatal defects is

if the text happens to end near the right margin, the symbol will be flush left, not flush right.

Therefore if you want an ending symbol exactly as the one from proof, you need either (see egreg's answer for details)

deal with glues and penalties.
pack your theorem-alike environment by adding \pushQED{your symbol} before and \popQED after. It is amsthm provides these two commands which take care of everything. (You can even use \qedhere).

Code:

\documentclass{book}
\usepackage{amssymb, amsmath, amsthm}

\newtheorem{ex}{Example}[chapter]

\let\Oldendex\endex%
\def\endex{\qed\Oldendex}%

\begin{document}
\begin{ex}
This is my example
\end{ex}
\end{document}

[Tex/LaTex] How to make “claim” environments look like “theorem” environment

Define a new module

There may be other (easier) ways, but you can create a new module, based on the existing one. It's not a lot of work, you just have to copy and rename some files, then do some small modifications to them:

Go to the LyX system directory, and from the layouts folder copy the two files theorems-ams.module and theorems-ams.inc, and paste them into the LyX user directory. (To find the path to these two directories, open LyX and do Help --> About LyX.)
Rename both files in the User directory, to for example theorems-ams-new.module and theorems-ams-new.inc. Doesn't matter what the filename is, just something other than the original.
Open the theorems-ams-new.module and make two changes:
1. In the first line, change the name of the module, i.e. from
```
#\DeclareLyXModule{Theorems (AMS)}
```
  to
```
#\DeclareLyXModule{Theorems (AMS) modified}
```
2. Further down, change
```
Input theorems-ams.inc
```
  to
```
Input theorems-ams-new.inc
```
  I.e., the filename should be same as the other file you just renamed.
Open theorems-ams-new.inc, and find the definition of the Claim environment (lines 257-271, in my version). There are two changes you should make.
1. In the second line of the definition, change the CopyStyle from Remark to Theorem (optionally Definition, see below). This defines how it is rendered in LyX.
2. In the sixth line of the definition, change
```
\theoremstyle{remark}
```
  to
```
\theoremstyle{plain}
```
  This changes how it is rendered in the PDF. The plain style typesets the 'heading' in bold font, and the body in italics, just like theorems. If you wish to have the body of the claim in roman font, use \theoremstyle{definition} instead. In this case you would probably also like to use CopyStyle Definition, as mentioned above.

Having done these modifications, you may need to reconfigure (Tools --> Reconfigure) and restart LyX. Now, instead of loading the 'Theorems (AMS)' module, load your own 'Theorems (AMS) modified'.

Using Local layout.

If this is a modification you need for just a single document, you can use Document --> Settings --> Local layout instead. Copy the entire definition of Claim to the Local layout, and do the changes described in point 4 above.

Best Answer

Caution!

Related Solutions

[Tex/LaTex] Change only the ending with renewenvironment

Code:

[Tex/LaTex] How to make “claim” environments look like “theorem” environment

Define a new module

Using Local layout.

Related Question