in vim, with
gUw
make the word uppercase, with
guw
make the word lowercase.
how I can convert in one map the upper to lower and the lower to upper?
If you're trying to invert case, you can use ~
. Normally this works only on the selection (e.g. visual mode), but if you want it to be more useful, then :set tildeop
so you can do ~w
or whatever movement command you like.