# Unnumbered theorem-like environments using thmtools

This produces an error (\* already defined):

\documentclass{report}
\usepackage{thmtools}
\declaretheorem[numbered=no]{theorem}
\begin{document}
Nothing.
\end{document}


Adding package amsthm solves the problem:

\documentclass{report}
\usepackage{amsthm}
\usepackage{thmtools}
\declaretheorem[numbered=no]{theorem}
\begin{document}
Nothing.
\end{document}


But what should I do if I would like to define my own proof environment (without changing my existing LaTeX code)? This produces an error (\proof already defined):

\documentclass{report}
\usepackage{amsthm}
\usepackage{thmtools}
\declaretheorem[numbered=no]{proof}
\begin{document}
Nothing.
\end{document}


I could use package ntheorem as the backend of package thmtools, but the documentation of thmtools says that some features do not work with ntheorem.

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Just don't define proof: the environment provided by amsthm has many good features. –  egreg Jan 10 '12 at 11:54
I would like to change the appearance of the displayed proof. –  ASdeL Jan 10 '12 at 11:59
Why don't you tell what changes you want to make? –  egreg Jan 10 '12 at 12:06
Do not know yet. I would like to play with the features of thmtools until I am satisfied with the result. –  ASdeL Jan 10 '12 at 12:16

## 1 Answer

You can simply fool LaTeX in thinking that proof is not defined:

\let\proof\relax
\declaretheorem[numbered=no]{proof}

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