Springer template svjour3 and unnumbered theorems

Question

I want to write an unnumbered theorem in a paper. I defined

\spnewtheorem*{theorem*}{Theorem}{\bfseries}{\itshape}

and expected to obtain

Theorem Theorem text

Instead, I obtained

Theorem Theorem text

i.e. the "Theorem" string is both boldface and italics. When I remove the star in \spnewtheorem, and define instead

\spnewtheorem{theorem*}{Theorem}{\bfseries}{\itshape}

I obtain

Theorem 1 Theorem text

as expected. I think this may be a bug in the definition of \spnewtheorem*. How does one correct it or notify it to Springer? Does anyone know?

My svjour3.cls file is dated "2010/11/25 v3.3" and my pdflatex executable is version "pdfTeX 3.141592653-2.6-1.40.24 (TeX Live 2022/Homebrew)"

Answer 1

How does one correct it?

I suggest you write

\spnewtheorem*{theorem*}{Theorem}{\upshape\bfseries}{\itshape}

i.e., add the directive \upshape.

Of course, you may also choose to contact Springer and alert them to an issue that may be a bug.

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Addendum, prompted by @egreg's comment: Just in case your document happens to modify the default font family and/or font encoding, it would be preferable to execute

\spnewtheorem*{theorem*}{Theorem}{\normalfont\bfseries}{\itshape}

i.e., to replace \upshape (used in the earlier instruction) with \normalfont. Of course, do make sure to execute \normalfont before rather than after \bfseries.

\documentclass{svjour3}
\spnewtheorem*{theorem*}{Theorem}{\normalfont\bfseries}{\itshape}

\begin{document}
\begin{theorem*} Theorem text \end{theorem*}
\end{document}