How can I use TexForm on built in variables, for instance,
TexForm[\[Del]^4]
This produces the following error:
Del::malfop: \[Del]^4 cannot be interpreted. It is not a known operator constructed from the del operator.
Del is a function, that has to act on something. If it does not, it will give an error. You can circumvent this behavior by typing it as a string:
TeXForm["\[Del]"]
\nabla