# Resolution of a problem concerning calligraphic fonts such as \mathcal or \pazocal

Although the question may seem very simple, I want to ask it because I wish to learn. I use a lot of packages for my book and unfortunately someone goes into conflict. For example, I can't use bm package. I was wondering because even if I put or not put a blank space after 2 to the symbol/command \boldsymbol{\mathcal{U}}, it doesn't separate (see picture). For the symbol \cdot next to the symbol \boldsymbol{\mathcal{A}} the blank space exists because I think the first one is an operator and the other one is a character. The empty space is created by default. My question is: to create space in these cases I must necessarily use space \,?

Here there are my MWE and the image:

\documentclass{article}
\usepackage{amssymb,mathtools,amsbsy}
\usepackage{newtxtext}
\begin{document}
$2 \boldsymbol{\mathcal{U}} \cdot \boldsymbol{\mathcal{A}}$
\end{document}

• Shape conflicts should be solved on a case by case analysis: in this case 2\,\boldsymbol{U} seems necessary; probably not for 2\boldsymbol{A}. – egreg May 10 at 11:21
• \, might be a bit too much, try \mkern1mu\boldsymbol{\mathcal{U}} (\,  is 3mu normally) – David Carlisle May 10 at 11:23
• @DavidCarlisle and egreg: Mine is just a mere curiosity and I thank you very much for your comments.Please could you give me an answer instead of a comment. Thank you very much. – Sebastiano May 10 at 11:24
• @egreg I also appreciate any response you may have. Best regards. – Sebastiano May 10 at 11:34

You need to do this manually, although of course you can define macros for the common ones in any document. \, might be a bit too much (although it is personal judgement) perhaps
2 \mkern1mu\boldsymbol{\mathcal{U}}

(\, is 3mu normally)