How to add different Q.E.D. symbols to different theorems?

Question

I have a series of theorem styles, two of them look like this:

\theoremstyle{definition}
\newtheorem{define}{Definition}

\theoremstyle{plain}
\newtheorem{theorem}{Theorem}

I want to add a \blacksquare to the end of each definition and a \square to every theorem (that is, in the last line aligned to the right).

I read about redefining the \qedsymbol to the desired value, but no theorem displays any symbol. Then, I tried wrapping the theorem into an additional environment, but then LaTeX throws missing $ errors at me. Both \newenvironment and NewEnviron produce these.

I would prefer to get the theorem system to add the symbol, anyway. So how can I specify the qed symbol to be used in your \newtheorem?

Answer 1

You can easily achieve what you want using thmtools as a front-end for amsthm; a little example:

\documentclass{article}
\usepackage{amssymb}
\usepackage{amsthm}
\usepackage{thmtools}

\declaretheorem[style=definition,name=Definition,qed=$\blacksquare$]{define}
\declaretheorem[style=plain,qed=$\square$]{theorem}

\begin{document}

\begin{define}
Test definition.
\end{define}
\begin{theorem}
Test theorem.
\end{theorem}

\end{document}