How to rename theorem when * is added

Question

I have the following in amsthm:

\newtheoremstyle{thm}
{}                % Space above
{}                % Space below
{}        % Theorem body font % (default is "\upshape")
{}                % Indent amount
{\bfseries}       % Theorem head font % (default is \mdseries)
{.}               % Punctuation after theorem head % default: no punctuation
{ }               % Space after theorem head
{}                % Theorem head spec
\theoremstyle{thm}
\newtheorem*{thm}{Théorème}
\newtheorem{nthm}{Le théorème}

The theorem names are in french, which forces us to create two different environments. One for numbered theorems and one for unnumbered theorems. Can I only create one environment (the thm one) so that when I insert the * the name automatically replaces to Theoreme instead of La theoreme? The code above is conflicting after other environments are defined, that's why I'm asking for this alternative. Thank you.

Answer 1

It's not clear what the problem is: it seems that you just want

\newtheorem*{thm*}{Théorème}
\newtheorem{thm}{Le théorème}

Full code.

\documentclass{article}
\usepackage{amsthm}

\newtheoremstyle{thm}
{}                % Space above
{}                % Space below
{}        % Theorem body font % (default is "\upshape")
{}                % Indent amount
{\bfseries}       % Theorem head font % (default is \mdseries)
{.}               % Punctuation after theorem head % default: no punctuation
{ }               % Space after theorem head
{}                % Theorem head spec

\theoremstyle{thm}
\newtheorem*{thm*}{Théorème}
\newtheorem{thm}{Le théorème}

\begin{document}

\begin{thm}
This is numbered, with no attribution
\end{thm}

\begin{thm}[Euclid]
This is numbered, with attribution
\end{thm}

\begin{thm*}
This is unnumbered, with no attribution
\end{thm*}

\begin{thm*}[Archimedes]
This is unnumbered, with attribution
\end{thm*}

\end{document}

Answer 2

Foreword: I'm merely executing what I understood from the question. Still, I consider that a theorem heading reading for instance "Le théorème 1" sounds a bit weird in French.Anyway, le client est roi. :-)

You can define two separate environments, say, theo and theo*, that respectively call nthm or thm. Not sure what you gain by doing so, though—except maybe clarity.

\documentclass{article}
\usepackage{amsthm}

\newtheoremstyle{thm}
  {}                % Space above
  {}                % Space below
  {}                % Theorem body font % (default is "\upshape")
  {}                % Indent amount
  {\bfseries}       % Theorem head font % (default is \mdseries)
  {.}               % Punctuation after theorem head % default: no punctuation
  { }               % Space after theorem head
  {}                % Theorem head spec

\theoremstyle{thm}
\newtheorem*{thm}{Théorème}
\newtheorem{nthm}{Le théorème}

\newenvironment{theo}[1][]{\nthm[#1]}{\endnthm}
\newenvironment{theo*}[1][]{\thm[#1]}{\endthm}

\begin{document}

  \begin{theo}
    This is a numbered theorem.
  \end{theo}

  \begin{theo*}
    This is an unumbered theorem.
  \end{theo*}

  \begin{theo}
    This is another numbered theorem.
  \end{theo}

\end{document}

With the optional argument:

\begin{theo}
  This is a numbered theorem.
\end{theo}

\begin{theo*}[Schreier]
  This is an unumbered theorem.
\end{theo*}

\begin{theo}[Bolzano]
  This is another numbered theorem.
\end{theo}