1 Answer

  1. Arthur- Reply

    2019-11-15

    There is no such problem using ntheorem instead of amsthm. Note ntheorem has a compatibilty mode with amsthm:

    \documentclass{scrartcl}
    \usepackage[T1]{fontenc}
    \usepackage[utf8]{inputenc}
    \usepackage[english]{babel}
    \usepackage{amssymb}
    \usepackage{empheq}
      \usepackage[thmmarks, amsmath, thref, amsthm]{ntheorem}
      \usepackage{dsfont}
    \theoremstyle{plain}
    \newtheorem{lemma}{Lemma}
    \theoremsymbol{\ensuremath{\square}}
    \newtheorem{lemmaqed}[lemma]{Lemma}
    
    \begin{document}
    
    \begin{lemmaqed}
      \begin{itemize}
        \item $a²+b²=c²$
        \item $a²+b²=c²$
      \end{itemize}
    \end{lemmaqed}
    
    \begin{lemmaqed}
      \begin{align*}
        a²+b²=c²
      \end{align*}
    \end{lemmaqed}
    
    \begin{lemmaqed}
      $a²+b²=c²$
    \end{lemmaqed}
    
    \end{document}
    

    enter image description here

    One might as well define a lemma environment, which by default has a qed-symbol at the end. This qed-symbol may be for deactivated for specific environments with the directive \NoEndMarks. Also, the symbol is easily customised on a per-theorem basis.

Leave a Reply

Your email address will not be published. Required fields are marked *

You can use these HTML tags and attributes <a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <strike> <strong>