[Tex/LaTex] Duplicating the amsthm proof environment

amsthmenvironmentstheorems

I am currently writing up some lecture notes and would like to have therefore a "\solution" environment which should work basically as the amsthm \proof environment, just writing "Solution." instead of "Proof." at the begin of a solution of an exercise. Of course I can achieve this by switching with

\renewcommand{\proofname}{Solution.}

resp.

\renewcommand{\proofname}{Proof.}

at the appropriate places. While this is working, I would find it nice to have a proper \solution environment which just replicates the \proof environment. Is there an easy way to do this?

Best Answer

Yes, there's an easy way. You can define your solution environment with "Solution" as the optional argument for proof:

\documentclass{article}
\usepackage{amsthm}

\newenvironment{solution}
  {\begin{proof}[Solution]}
  {\end{proof}}

\begin{document}

\begin{proof}
test.
\end{proof}

\begin{solution}
test.
\end{solution}

\end{document}

enter image description here

Related Solutions

[Tex/LaTex] ntheorem with the [amsthm] option ignores styling of a theorem environment

It is possible to "lift" the proof environment code from ntheorem:

\documentclass{article}
\usepackage[thmmarks]{ntheorem}% http://ctan.org/pkg/ntheorem

\makeatletter
\newcommand{\openbox}{\leavevmode
  \hbox to.77778em{%
  \hfil\vrule
  \vbox to.675em{\hrule width.6em\vfil\hrule}%
  \vrule\hfil}}
\gdef\proofSymbol{\openbox}
\newcommand{\proofname}{Proof.}
\newcounter{proof}\newcounter{currproofctr}\newcounter{endproofctr}%
\newenvironment{proof}[1][\proofname]{
  \th@nonumberplain
  \def\theorem@headerfont{\itshape}%
  \normalfont
  %\theoremsymbol{\ensuremath{_\blacksquare}}
  \@thm{proof}{proof}{#1}}%
  {\@endtheorem}
\makeatother

\theoremstyle{plain}
\theoremheaderfont{\normalfont\itshape}
\theorembodyfont{\normalfont}
\newtheorem*{myenv}{Note}

\begin{document}
\begin{myenv}
The quick brown fox jumps over the lazy dog. The quick brown fox jumps over the lazy dog. The quick brown fox jumps over the lazy dog.
\begin{proof}
This statement is true, because the fox did jump over the lazy dog.
\end{proof}
\end{myenv}
\end{document}

ntheorem with amsthm proof environment

The QED-symbol is displayed when using the thmmarks package option of ntheorem. In ntheorem this is manually defined in \openbox, and subsequently used as \proofSymbol.

[Tex/LaTex] An inline exercise environment

Here is an implementation that provides a \exinline command, taking a label argument to produce the relevant text.

Sample output

\documentclass{article}

\usepackage{amsthm}

\newtheorem{theorem}{Theorem}[section]
\newtheorem{exercise}[theorem]{Exercise}

\newcommand{\exinline}[1]{(\refstepcounter{theorem}Exercise~\thetheorem\label{#1})}

\begin{document}

\section{Euler's Theorem}

Some text.

\begin{theorem}[Euler]
  \label{thm:Euler}
  This is Euler's theorem.
\end{theorem}

\begin{proof}
  The proof of this theorem is left as an exercise \exinline{ex:Euler}.
\end{proof}

\begin{exercise}
  \label{ex:extra}
  Reformulate the theorem.
\end{exercise}

Here is the solution to Exercise~\ref{ex:Euler}.  By\dots

Note that Exercise~\ref{ex:extra} requires you to provide another formulation
of Theorem~\ref{thm:Euler}.

\end{document}

Note in this example Exercises and Theorems share the same counter. If that is not the case, you need to replace the theorem counter in definition with the appropriate counter, and change \thetheorem correspondingly. E.g. if exercises have their own number, declared via \newtheorem{exercise}{Exercise}[section], the command definition should read

\newcommand{\exinline}[1]{(\refstepcounter{exercise}Exercise~\theexercise\label{#1})}

If you are using cleveref for references then a small modification is needed to the refstepcounter command so \cref picks up the correct name.

\documentclass{article}

\usepackage{amsthm}
\usepackage[capitalize]{cleveref}

\newtheorem{theorem}{Theorem}[section]
\newtheorem{exercise}[theorem]{Exercise}

\newcommand{\exinline}[1]{(\refstepcounter[exercise]{theorem}Exercise~\thetheorem\label{#1})}

\begin{document}

\section{Euler's Theorem}

Some text.

\begin{theorem}[Euler]
  \label{thm:Euler}
  This is Euler's theorem.
\end{theorem}

\begin{proof}
  The proof of this theorem is left as an exercise \exinline{ex:Euler}.
\end{proof}

\begin{exercise}
  \label{ex:extra}
  Reformulate the theorem.
\end{exercise}

Here is the solution to \cref{ex:Euler}.  By\dots

Note that \cref{ex:extra} requires you to provide another formulation
of \cref{thm:Euler}.

\end{document}

This produces the same output as the first example, with cleveref correctly providing the names.

Best Answer

Related Solutions

[Tex/LaTex] ntheorem with the [amsthm] option ignores styling of a theorem environment

[Tex/LaTex] An inline exercise environment

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