\subparagraph with llncs

Question

I can't get \subparagaph to work properly in my file

\documentclass[runningheads]{llncs}


\usepackage{hyperref}
\renewcommand\UrlFont{\color{blue}\rmfamily}
\usepackage{thm-restate}
\usepackage{amsmath,amssymb}
\usepackage{comment}

\usepackage[algosection,ruled,lined,linesnumbered,longend]{algorithm2e}


%\usepackage{enumerate}
\newcommand{\mypara}[1]{\noindent{\bfseries #1.}}


\newcommand{\0}{\mathbb{0}} 
\newcommand{\1}{\mathbb{1}} 
\newcommand{\C}{\ensuremath{\mathcal{C}}}
\newcommand{\simp}{sim}

\newcommand{\ECT}{\ensuremath{\textsc{ECT}}}
 
 
\begin{document}
asdfasdf 
\subparagraph{adsfasfdsafdafdsfdasfdsf}



\end{document}

Where llncs is the Springer LNCS format file https://www.overleaf.com/3138125197nxqpxwfdbfyb I can't find the official link right now

Answer 1

\subparagraph is explictly disabled by the class But there is a bug in the code used to disable it.

The intention is that you get the warning

LLNCS warning: You should not use \subparagraph with this class

but what happens is that you get a loop and the warning is repeated until you run out of memory.

LLNCS warning: You should not use \subparagraph with this class
LLNCS warning: You should not use \subparagraph with this class
LLNCS warning: You should not use \subparagraph with this class
LLNCS warning: You should not use \subparagraph with this class
LLNCS warning: You should not use \subparagraph with this class
LLNCS warning: You should not use \subparagraph with this class
LLNCS warning: You should not use \subparagraph with this class
LLNCS warning: You should not use \subparagraph with this class
LLNCS warning: You should not use \subparagraph with this class
LLNCS warning: You should not use \subparagraph with this class
LLNCS warning: You should not use \subparagraph with this class
LLNCS warning: You should not use \subparagraph with this class
! TeX capacity exceeded, sorry [grouping levels=255].

The llncs.cls file has

\renewcommand\subparagraph[1]{\typeout{LLNCS warning: You should not use
                  \string\subparagraph\space with this class}\vskip0.5cm
You should not use \verb|\subparagraph| with this class.\vskip0.5cm}

You can not use \verb in the argument of a command so here the \verb does not stop \subparagraph calling itself so you get a loop. It should be

\renewcommand\subparagraph[1]{\typeout{LLNCS warning: You should not use
                  \string\subparagraph\space with this class}\vskip0.5cm
You should not use \texttt{\string\subparagraph} with this class.\vskip0.5cm}

You probably do not need \subparagraph it should only be used to make 6th level headings after \chapter, \section, \subsection, \subsubsection, \paragraph and few documents need that many section levels.