# Overset and mathbb collision

I have ran into really funny trouble trying to use \overset and \mathbb the same time. I need to do something like this:

but with the T as mathbb, i.e. \mathbb{\overset{m}T}_{ij}. When I try it, this happens:

• Why?
• How can I make it work?

Note: Putting \overset before the mathbb doesn't work.

You need to put the T inside the overset:

\overset{m}{\mathbb{T}}_{ij}

• Done. The answer was posted so immediately I couldn't do that cause of 10 mins non-optional delay. – Victor Pira Dec 2 '15 at 15:07

While the accepted answer provides the solution, I wish to address the "Why?" issue in the question.

The \mathbb alphabet is defined by amsfonts.sty as

\DeclareSymbolFontAlphabet{\mathbb}{AMSb}


which basically means "use the glyphs from the font AMSb" (which is also declared by amsfonts). The font AMSb contains the blackboard-bold capital letters and a whole bunch of other symbols. So when you type \mathbb{T} you obtain what you expect; but \mathbb{m} looks for the glyph in the slot "6D, which is not a small blackboard-bold m (it doesn't even exist in AMSb) but rather the symbol \gtrdot, thus explaining the weird result.

• Thank you very much, I really appreciate that someone picks the "Why" part as well! – Victor Pira Dec 2 '15 at 16:49
• Incidentally, is there a package that provides blackboard-bold lowercase (or even Greek) letters which are consistent with the AMS style? The ones I've seen don't match up very closely. – David Zhang Dec 2 '15 at 21:26