How can I use \centerdot while defining type of bullet?

Question

The problem:

I get an undefined control sequence error when trying to define the bullet type of the second-level items. I'm using:

\renewcommand{\labelitemii}{$\centerdot$}

Notes:

• I've read in some pages (e.g. Latex symbols) that \centerdots is a valid symbol.

• My document compiles fine without that line. It also works fine if I use another type, like \Rightarrow or \cdot. For example

  \renewcommand{\labelitemii}{$\cdot$}
  

• The error message is:

  ! Undefined control sequence.
  <recently read> \centerdot
  l.114 \item C
  ontienen los operandos vectoriales en máquinas de registros
  The control sequence at the end of the top line
  of your error message was never \def'ed. If you have
  misspelled it (e.g., `\hobx'), type `I' and the correct
  spelling (e.g., `I\hbox'). Otherwise just continue,
  and I'll forget about whatever was undefined.
  

• The line which the first error points to is:

  \begin{itemize} % first level
     \item \textbf{Registros Vectoriales}
     \begin{itemize} % second level
         \item Contienen los operandos vectoriales en máquinas de registros % ERROR
     ...
  

Answer 1

I'd avoid loading mathabx just in order to get a square bullet:

\documentclass{article}
\usepackage{enumitem}

\DeclareRobustCommand{\sqbullet}{%
  \raisebox{.3ex}{\rule{.3em}{.3em}}%
}

\setlist[itemize,2]{label=\sqbullet} % similar to \renewcommand{\labelitemii}{\sqbullet}

\begin{document}

\begin{itemize} % first level
   \item \textbf{Registros Vectoriales}
   \begin{itemize} % second level
       \item Contienen los operandos vectoriales
   \end{itemize}
\end{itemize}

\end{document}

Answer 2

You need to do \usepackage{amssymb} or \usepackage{mathabx} in order to use \centerdot. Note that the latter will redefine a lot of other mathematical symbols.