Command `\Bbbk' already defined. ...ol{\Bbbk} {\mathord}{AMSb}{"7C} when I try to run the mnras_template.tex

Question

Command \Bbbk' already defined. ...ol{\Bbbk} {\mathord}{AMSb}{"7C} when I try to run the mnras_template.tex

It worked at first and then is updated some of the packages and now it will not run without commenting out some of the packages.

Answer 1

The issue is in their template file (the MWE is below because when I tried to include the MWE in the question, my edit was rejected).

My solution:

Comment out or better delete the line saying \usepackage{amssymb} because it clashed with the updated version of the MNRAS package.

Solution proposed by the MNRAS publishers:

Move the line

\usepackage{newtxtext,newtxmath}

to the end of the preamble. This works with or without loading amssymb separately. Hopefully, a new version of the template on CTAN will reflect this change as well.

MWE:

\documentclass[fleqn,usenatbib]{mnras}

% MNRAS is set in Times font. If you don't have this installed (most LaTeX
% installations will be fine) or prefer the old Computer Modern fonts, comment
% out the following line
\usepackage{newtxtext,newtxmath}
% Depending on your LaTeX fonts installation, you might get better results with one of these:
% \usepackage{mathptmx}
% \usepackage{txfonts}

% Use vector fonts, so it zooms properly in on-screen viewing software
% Don't change these lines unless you know what you are doing
\usepackage[T1]{fontenc}
% \usepackage[utf8]{inputenc}

% Allow "Thomas van Noord" and "Simon de Laguarde" and alike to be sorted by "N" and "L" etc. in the bibliography.
% Write the name in the bibliography as "\VAN{Noord}{Van}{van} Noord, Thomas"
\DeclareRobustCommand{\VAN}[3]{#2}
\let\VANthebibliography\thebibliography
\def\thebibliography{\DeclareRobustCommand{\VAN}[3]{##3}\VANthebibliography}


%%%%% AUTHORS - PLACE YOUR OWN PACKAGES HERE %%%%%

% Only include extra packages if you really need them. Common packages are:
\usepackage{graphicx}   % Including figure files
\usepackage{amsmath}    % Advanced maths commands
\usepackage{amssymb}    % Extra maths symbols  <----- DELETE THIS LINE

\title[Short title, max. 45 characters]{MNRAS \LaTeXe\ template -- title goes here}

\author[authors running]{
First Author$^{1}$\thanks{E-mail: email}
\\
% List of institutions
$^{1}$Institution
}

% These dates will be filled out by the publisher
\date{Accepted XXX. Received YYY; in original form ZZZ}

% Enter the current year, for the copyright statements etc.
\pubyear{2020}

% Don't change these lines
\begin{document}
\label{firstpage}
\pagerange{\pageref{firstpage}--\pageref{lastpage}}
\maketitle

\begin{abstract}
Abstract...
\end{abstract}

\begin{keywords}
keyword1 -- keyword2 -- keyword3
\end{keywords}

\section{Introduction}

Text...


\bibliographystyle{mnras}
\bibliography{example} % if your bibtex file is called example.bib

% Don't change these lines
\bsp    % typesetting comment
\label{lastpage}
\end{document}

Answer 2

As both newtxmath and amssymb pkgs define \Bbbk, you simply need to add \let\Bbbk\relax in between them to disable the preceding definition. Say you want to keep the definition in newtxmath, then the following should do.

\usepackage{amssymb}
\let\Bbbk\relax
\usepackage{newtxmath}

Answer 3

It not work. Hereis mine:

In mymain.tex

 \documentclass[pifootnote,degree=doctor,openright,oneside,fontset=fandol]{ccnuthesis}
   \usepackage{ccnuthesis}
   \usepackage{comment}
   \usepackage{tikz}
   \usepackage{slashed}
   \usepackage{IEEEtrantools}
   \usepackage{amsfonts}
   %%\let\Bbbk\relax
   \usepackage{amssymb}
   ...

In ccnuthesis.cls

   ...
   \RequirePackage{amsmath}
   \RequirePackage[defaultsups]{newtxtext}
   \RequirePackage{newtxmath}
   ...

In ccnuthesis.sty

 \ProvidesPackage{ccnuthesis}[2017/12/28 4.1 put any packages you would like to use here]
   \RequirePackage{amssymb}
   ...

1. I've move \usepackage{ccnuthesis} after \usepackage{amssymb}. Error appear!
2. I've add %%\let\Bbbk\relax in the front ling of \usepackage{amssymb}. Error appear!