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`

?

## Best Answer

You can easily achieve what you want using

`thmtools`

as a front-end for`amsthm`

; a little example: