I want to be able to make several symbols bold by grouping them within some sort of bolding command. I can make a single symbol bold by using (for example)
\boldsymbol \phi
but I want to be able to bold several symbols, something like:
{\boldsymbol \phi \vee \psi}
This doesn't work. I've tried \bf in a group as well, which Mathjax says it supports, but it doesn't.
How can I achieve this, I don't want to have to put \boldsymbol on every single symbol!
Use \boldsymbol{\phi \vee \psi}. Note that \boldsymbol is a macro that takes an argument (like \mathbf{}), not a switch (like \bf). Also, note that in TeX, \bf only affects certain symbols (basically, just the letters and numbers), and MathJax does the same. So in TeX, as well as MathJax, {\bf \phi \vee \psi} will produce the same thing as \phi \vee \psi.