The VARS() command will list the variables to which you have assigned values or assumptions. If you begin by entering
a := 1
and
anothervar := 2
then
VARS()
will return
[a, anothervar]
The purge command will clear the values and assumptions you make on variables. You can clear the values and assumptions you have made on all variables with
restart
or
rm_all_vars()
command.