I have included the package amsmath as required to defined a new theorem/corollary (without number), but I keep having the following error:

! LaTeX Error: Command \* already defined.

Now, these are the packages I am including, if that can help:


And then I am tring to use the new command with:

  • You need \usepackage{amsthm} in order to use \newtheorem*
    – egreg
    Commented May 19, 2015 at 21:31
  • You do need amsmath if you're writing a mathematical document. It's just not sufficient.
    – egreg
    Commented May 19, 2015 at 21:33

1 Answer 1


The package you need is amsthm (besides the recommended amsmath).

Add \usepackage{amsthm} and all will go flawlessly.

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